Amazon has declared July 11 to be Prime Day, but the savings will kick off even earlier.

Starting at 9 pm ET on July 10, the site will begin offering new deals as often as every five minutes, the company said. The sales event will continue for 30 hours and be offered to shoppers in 13 countries. Some promotions will begin as early as Thursday.

This is the third time Amazon will be hosting the self-created sales holiday. Last year, Prime Day sales rose more than 60 percent from the prior year. In the U.S., orders were up more than 50 percent.

The first Prime Day was held on July 15, 2015, as a way to mark the company's 20th anniversary, and it proved to be such a success boosting sales and bringing in new Prime members that the company did it all again on July 12, 2016.

Since then, Amazon's base of Prime members has only grown in size, which may make it a bit harder to find new shoppers to bring into the fold. But that isn't stopping Amazon from trying. Prime members tend to be several-times more valuable to the company than non-member shoppers, and make up a sizable portion of its e-commerce sales.

Last year, Amazon spread out its deals further into the day than it did in year one, including more than 800 limited-time "Lightning Deals" that it launched in the evening hours.

This year, the e-commerce giant is once again upping the ante, proclaiming that there will be "hundreds of thousands of deals" on July 11. About 40 percent of this year's "Lightning Deals" will come from small businesses and entrepreneurs, the company said.

As usual, Amazon sees the sales event as way to promote its other products and services. For example, to promote its Amazon Echo and other related voice-activated products, there will be Alexa-exclusive deals, and to promote its Amazon Fire TV, there will be numerous TV deals.

The promotions that start Thursday focus on Amazon's various entertainment services. They include:

Prime members can sign up for Amazon Music Unlimited for four months for 99 cents.

If you stream video on your TV for the first time, you can receive $10 to shop on Amazon.com on or before Prime Day.

Kindle Unlimited memberships will be as much as 40 percent off.

Audible memberships will be 40 percent off for six months, or $8.95 per month.

Prime members can see a sneak peek of the second season of "The Grand Tour."

Also, as Amazon tries to push further into staple, grocery items — a move that will be bolstered by its acquisition of Whole Foods, announced earlier this month — the company plans to sell various food and household items for as much as 35 percent off with onsite coupons in Prime Pantry.

"Our members love Prime Day and we were thrilled by the response over the last two years," said Greg Greeley, vice president of Amazon Prime, in a press release. "Every side of our business is working to deliver more deals for a record number of shoppers."

No doubt, rivals such as Wal-Mart will try to make the most of the Prime Day buzz by hosting their own sales, as they did last year.

Since Prime Day 2016, the world's largest retailer has stepped up its own e-commerce efforts with its acquisition of Jet.com and several other online retailers. As a result, it will be interesting to see if Wal-Mart approaches the event with any fresh ideas.

No doubt the flurry of buying is welcomed by retailers in July, when sales tend to cool ahead of a back-to-school shopping blitz and the holiday season, the two busiest shopping periods on the retail industry's calendar.

For investors, the day also marks a buying opportunity, according to Deutsche Bank analyst Lloyd Walmsley. He said Wednesday that Amazon shares have outperformed the S&P 500 by 6 percentage points between the day the company announces the event and Prime Day itself.

Amazon shares closed Wednesday up 1.4 percent at $990.33. The stock, which breached the $1,000-mark earlier this year, has gained more than 32 percent year to date and nearly 40 percent over the past year.

Early signs hint that the event could grow in 2017. In a nationwide survey of 1,200 U.S. consumers by Market Track, 58 percent said they would shop Prime Day deals, up from 34 percent who said they would participate last year.

Market Track attributed the growth to Amazon's increased participation rate in the Prime membership program and publicity surrounding the previous events, which was bolstered as more companies participated in their own events.

"Competing retailers have learned a lot about Prime Day over the past two years, yet the event is very much still in its youth," said Ryne Misso, director of marketing at Market Track.