I agree -- only so much time left, but that will work fine. I did it to my laptop two months ago, just because the Win7 which came to me on a Gateway laptop refurb as a branded Dell version. I've had more trouble with branded OS install discs than regular white-box OEMs, so real or not, I chose to replace them.
Of course, if you look at the options you have -- OEM white-box Win 7; downloaded fully-legal with activation key -- the difference in price may not be that great. You might on that basis decide only to purchase the Win10 OEM.
But you may be disinclined to cut the umbilical to Win7 -- like me. So get the Win7 white-box, install and activate it, download the Win10 Media Creation Tool, download Win 10 for USB or ISO, and install it as well using the same activation key.