Windows 10 for phones is already being developed, but its development is behind the one for the PC version, so the two won’t go live together in the summer of 2015. Microsoft confirmed this at BUILD 2015, but the company refused to provide any specifics, as depending on how fast development goes, it could push back the launch until the product is ready.

What we’re hearing, however, is that Microsoft is targeting a fall 2015 release date for Windows 10 for phones, possibly in September or October, but there are several things that we should keep in mind when talking about the launch date of the new mobile platform.

First and foremost, a fall 2015 unveiling would align with previous rumors pointing that a flagship device running Windows 10 for phones would be launched in autumn, and there’s no doubt that Microsoft would introduce both projects together. A flagship would be the best way to show the full potential of a new platform, so expect Windows 10 for phones and a Lumia 940 to see daylight at the same time.

But there’s something that might actually ruin your day if you’re a Windows Phone enthusiast. Microsoft is reportedly planning the launch of Windows 10 for phones in stages, meaning that only some devices would get it at first, with the rest to receive it at pre-defined intervals.

Rollout to complete in 2016

So if Microsoft indeed decides to launch Windows 10 for phones in the fall of 2015, only some Lumia models will get it in the beginning. The rollout could be completed in early 2016, so by this time next year, all Windows Phone devices should already be running Windows 10.

The biggest problem with this gradual release is the disappointment that some users might feel for not getting Windows 10 among the first. This already happened two times in the last 12 months, so Microsoft might want to reconsider this strategy before launching Windows 10.

First, it was the Denim update, whose rollout started in December 2014 but lasted until February/March 2015 for some devices across the world. And then, it was the Windows 10 for phones preview unveiling that only took place on six Lumia models initially, causing outrage in the Windows Phone community.

Keep in mind that these are all just rumors for the time being and Microsoft can change this strategy and release dates at any moment, so don’t take anything for granted until it’s official.