Last time I checked, a few days ago, the free update was still working. If you EVER want to be able to do this, I'd do it now. Once you are on Windows 10, indications are that your digital entitlement is indefinite, unlike Windows 7 which WILL lose support at some point. Also at some point, you will NOT be able to take advantage of the free upgrade. It will happen, the only question is when.
https://www.slashgear.com/free-windows-10-upgrade-still-available-but-you-need-to-be-quick-15515733/