Earlier this month, Microsoft announced Windows 10 for PCs will launch on July 29. The company did not share, however, when exactly other editions would arrive. Windows 10 Mobile and Windows 10 Mobile Enterprise, the successors to Windows Phone 8, are widely expected to ship in the next few months.

Microsoft has previously explained that Windows 10 will launch on PCs first, and will arrive for phones sometime later. Other devices like Surface Hub and Microsoft HoloLens will follow afterwards as well.

The “sometime later” apparently means “late next quarter,” according to a recent presentation Microsoft made to one of its partners. Neowin managed to obtain the slide with those three key words, and concluded this means a “late September” launch:

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Yet “late next quarter” does not necessarily mean “late September.” For all we know, Windows 10 Mobile will arrive at the start or in mid-September. In fact, because Microsoft is not sharing a date yet, it’s also possible the launch will get pushed back.

The release gap between PC and phone versions makes a lot of sense. Windows naturally has a much bigger user base on the PC than on the phone, so Microsoft wants to focus getting users to upgrade there first.

Current test builds of Windows 10 for phones are behind their PC counterparts in terms of features and stability. The reason for this is simple: Windows 8 was released before Windows Phone 8, so the latter simply has a late start. Furthermore, Windows 10 for phones also has to go through carrier testing, something Microsoft naturally has little control over in various parts of the world, meaning updates will likely come even later after launch.

Either way, don’t expect Windows 10 Mobile and Windows 10 Mobile Enterprise to show up for a few more months. It will likely be timed with the launch of Microsoft’s two rumored flagship Lumia smartphones.