Investing in expensive new gear can be a tricky proposition; buy at the wrong time, and you could miss out on innovative features, better performance, price drops, and more. But don't worry! With a slate of Apple announcements coming next week, we're here talk you through the best time to upgrade your iPhone, MacBook, iMac, and more.

On Monday, in addition to detailing its much-anticipated watch, Apple could introduce another brand new product: a totally redesigned, 12-inch, Retina display MacBook Air. Apple enthusiasts have been anxiously—and rightly—expecting a Retina MBA ever since the company introduced the MacBook Pro with Retina display three years ago. It looks like you'll be rewarded for holding off, though; even if the Retina MacBook Air doesn't make an appearance on Monday, the Wall Street Journal reports that it will start shipping sometime in the next few months.

The Retina MacBook Air saga is a reminder that strategic upgrade timing pays off. With that in mind, we’ve prepared solid guidelines on when it’s definitely time to pony up for a new Apple gadget, and when you can squeeze out a few more months, or years, out of the device.

iPhone

For years, new iPhones reliably arrived in the summer, on the heels of Apple’s annual developer conference. These days, though, Apple drops its new handsets in fall, usually late September or early October. The benefit of this timing is two-fold: It gives third-party developers a few months to make sure their apps take advantage of the latest iOS features, and it ensures that the bright and shiny newness aligns neatly with the spendy holiday shopping season. So if you’re eligible for an upgrade in June or July, just hold out a few more months until the year’s latest handsets drop.

With that in mind, we suggest updating your iPhone every two years. Your hardware can easily hold up that long, and the latest version of iOS should still run smoothly. Wait much longer, and wear and tear start taking their toll on both. Battery life starts to go downhill. The software experience degrades; things slow down, and you’re more likely to suffer crashes and hangups.

If you can swing it, you should also try to align your upgrades with Apple's "tick-tock" iPhone release cycle. Traditionally, every two years the company announces a major iPhone overhaul, while the intervening years are largely iterative. Think iPhone 5 (tick) to iPhone 5S (tock). You'll end up with a lot less feature-lust if you stick with the ticks.

If you do decide to hold onto your iPhone for more than two years, you should at the very least wait a few weeks to a month before downloading major iOS updates as they come. Older devices tend to experience more compatibility issues and bugs, which usually get smoothed out over time. That doesn't mean you should just stay on iOS 8 forever, though; keeping your iOS version as up-to-date as possible will at the very least keep your security patches up to date.

Bottom line: Wait until fall to upgrade if you can, and try to line up your purchases with Apple's biennial overhauls instead of iterative improvements.

Josh Valcarcel/WIRED

iPad

The iPad is a curious beast. While it still sells better than any other tablet, demand has lately slowed. That's partly because of increased competition from Amazon and others, but you don't need to buy a new tablet as frequently as you do a new smartphone.

If you currently have an iPad with a non-Retina display—that's the first or second generation—you should go ahead and upgrade. Apple typically refreshes the line in late fall, so you're in little danger of timing remorse if you buy today, and the experience is fundamentally, unquestionably better.

Otherwise, we think people should be able to hold onto their iPads for around four years before upgrading to a new one. The main benefits of newer iPads are faster processing and graphics performance, a higher resolution Retina display, and a lighter weight, all of which are welcome but not strictly necessary or even particularly noticeable in day to day use. As long as your iPad chugs along at a speed you’re comfortable with and doesn’t suffer from any egregious battery drain issues, there’s no real reason to upgrade.

There is one iPad upgrade wild card to consider. A larger 12.9-inch "iPad Pro" could arrive this fall, so you might want to hold off until then if you like your tablets super-sized.

Bottom line: If you have a third-generation or newer iPad, you're fine until you experience a noticeable performance drop-off. When the time comes to pony up for a new one, wait until fall.

Ariel Zambelich/WIRED

MacBook Air

Given the pace of innovation and the wear and tear you’ll put on your notebook, we suggest updating your MacBook Air more often than your iPad: Every three years should be right for most people.

While you used to be able to squeeze a few more years out of your MacBook by swapping in new guts, today's MacBook Airs (and most other contemporary Apple products) are constructed such that it’s nigh on impossible to replace individual components. However, if you do want to give it a shot, Other World Computing offers a DIY SSD solution for 2010-2013 model Airs. This will eke a few more years out of your ultraportable, assuming you don't break something delicate while you tinker.

When you do buy new, pile in as much RAM and as fast a processor as you can afford. That will help ensure that your rig can keep up with your needs for years to come—as well as the demands of future versions of OS X.

As for time of year, the update cycle for the Air can be sporadic, partly because it's largely dependent on Intel's processor upgrades. As we said earlier, a new 12-inch Retina MacBook Air and spec bumps for non-Retina versions are right around the corner, so hold off until they're official. And even then, remember that the first generation of a new line often suffers from some issues (a fraction of original Retina MacBook Pros suffered from display problems like ghosting). Better to hold off until any launch headaches have cleared up.

Bottom line: Don't buy a MacBook Air before a Retina display model is official, which could happen as soon as Monday. Generally, you should expect to get at least three years out of a tricked out MBA, with refreshes coming late spring/early summer.

Macbook Pro Retina 15inch. Photo: Josh Valcarcel Josh Valcarcel/WIRED

MacBook Pro

Your MacBook Pro is more powerful and robust than a MacBook Air, which conveniently makes it more future-proof. You should be able to hold onto it for at least four years. As with the MacBook Air, we suggest maxing out the memory and processor options as much as your budget will allow.

As with the MBA, it’s become difficult to predict when a new version will arrive, due to Apple's reliance on when Intel drops its latest chipsets. However, the last update to the Pro was last July, so we’d expect this year’s update to fall in the April to July time frame.

Bottom line: A well-equipped MacBook Pro should last you about four years. When you do decide to upgrade, look for the latest model to hit late spring/early summer.

Josh Valcarcel/WIRED

iMac

You don’t invest in an iMac expecting to swap that thing out every other year. And in fact, if you opt for higher memory when you grab your desktop computer, you can expect to get as much as seven years out of it. There's some comfort in knowing that the latest version of OS X supports iMacs dating as far back as mid 2007.

Apple updates the form factor of its desktop offering every two to four years, and of late, has been showing off its latest all-in-one offering in late fall. The last major hardware overhaul shipped in 2012. In 2014, Apple only added a 5K Retina version to the mix, leaving its non-Retina iMacs unchanged. This fall, we should expect internal updates to both the 5K Retina and non-Retina iMacs.

Bottom line: If you have an iMac that works, sit tight, at least until pricing on the Retina display models comes down from the stratosphere. When it does come time to upgrade, wait until the fall to make sure you've got the latest guts.

Ariel Zambelich/WIRED

Apple TV

Apple's living room "hobby," this set-top box generally sees a hardware refresh every two to three years. While we saw a processor redesign in 2013, we haven't had a major Apple TV update since 2012, when it finally embraced 1080p streaming.

While Apple's offered a steady supply of software updates and new channel offerings over the years, we're definitely due for a substantial product overhaul—maybe as soon as at Monday's Apple Watch event, but more likely later this year.

There are a lot of rumored features incoming; Apple TV will likely eventually act as a hub for your various HomeKit smart devices. There are also signs that Apple could introduce gaming on future Apple TV hardware, especially given the advances competitors like Google, Amazon, and even Razer have made in that field.

The real Apple TV feature you should wait for, though, is 4K streaming. That's going to become the prevailing standard in a few short years, and anything short of that won't be as future-proof as you'll want in the long run.

Bottom line: Irregular updates make release timing difficult to gauge, but you should hold out on buying a new Apple TV until Apple adds 4K support, unless more niche features like set-top box gaming or smart home coordination are a must-have.