If you haven't upgraded to Windows 10 TH2 you will get a 2 day countdown from the GWX (Get Windows 10 Nagware).
I decided to change my date/time in my UEFI BIOS and I got this.
The Windows 10 TH2 Media Creation Tool seems to be unphased by the date change however.
Note that the Windows 10 TH2 Media Creation Tool seems to be completely unphased by the fact that the system's date has changed. This may be because either it connects to Microsoft Servers and the servers report the true date or alternatively because Microsoft have no intention on stopping the Free Upgrade. More testing needs to be done.
More details in this video: