The distribution of 8.1 will include a few steps, including getting it into manufacturers’ hands, pushing updates through carriers and most tantalizing, the Developer Preview Program. That program, accessed through an app on the Windows Phone Store and open to anybody with a free App Studio account, will allow everyone to install Windows Phone 8.1 on any Windows Phone 8 device weeks before “official” carrier updates.

While Windows Phone 8.1 is going to be the big news, a lot of you are only concerned with one thing: When do you get it?

It’s Monday morning, just days before Microsoft’s Build conference kicks off in San Francisco. Windows Phone 8.1 is one of a few announcements expected by Redmond, with Nokia following up later in the day with some their own press event .

A few days ago, we reported that this program was set to launch in ‘late April’. That was certainly a vague deadline, but the important thing to take away was that it won’t be released the same day as the Build announcement on April 2. We now have confirmation that the planned release schedule for the Preview for Developer program should be Thursday, April 10, just over one week from the Build reveal. That falls in line with our original report on the core of 8.1 wrapping development by Microsoft.

The Preview for Developers version of Windows Phone 8.1 looks to be the latest, with the final core of the OS and the hottest patches, referred internally as Quick Fix Engineering (QFE) update #5.

Assuming this schedule does not change, anyone and everyone who opts in to the Preview Program can have Windows Phone 8.1 on their current phones starting that day. Later, when the official update rolls out over-the-air – following carrier approval – those Preview devices will update to the latest version of the OS and firmware.

We should of course caution that Microsoft could change things at the last minute, but internal planning schedules show April 10 as the current date.

More details about the Developer Preview Program can be found on the Windows Phone Blog, which describes the features and limits of the older Update 3 preview.