Owners of Microsoft devices running Windows 8.0 and Windows 8.1 must be losing patience waiting for the Windows 10 Mobile update after a few reports claimed the Lumia 535 and Lumia 640 have already received the software.

It was reported that T-Mobile Poland had started rolling out the Windows 10 Mobile OTA (over-the-air) update to Lumia 640 devices, and that T-Mobile variants of the Lumia 535 in Latin America have got the software. But there has been no update on it since the report surfaced and Microsoft has not confirmed it either, which hints at a possibility that the software has not been rolled out yet.

So, when can Lumia device owners expect the new software? Any time. Maybe this week.

According to a report by WMpoweruser, T-Mobile Moderator has revealed on the company's discussion forum: "Windows 10 Mobile update start between the 14th and 21st January, and will take the OS up to version 10586.63 (sic)". 

Meanwhile, Lumia Help has tweeted that the software will be rolled out any time. A report by WMpoweruser has claimed Microsoft has started working on an app called Uprgade Advisor to let users check if their devices are eligible to get the Windows 10 Mobile update when it is rolled out. However, the app has not been made available to the public.

Microsoft has announced that its devices like Lumia 430, Lumia 532, Lumia 535, Lumia 540, Lumia 640, Lumia 640 XL, Lumia 735, Lumia 830 and Lumia 930 will receive the Windows 10 Mobile update. It also revealed that all Windows 8.0-based phones will get the software.