http://www.howtogeek.com/253901/get-windows-10-for-free-after-july-29th-with-a-little-prep-now/Was looking for a way to save the free upgrade for later. And found this neat article on exactly what i was looking for.
I know some people are still leery of the upgrade since they like win 7 so much, this seems to be a perfect way to keep both options open with a little bit of work and effort.
Going to do this myself in the next couple days.
TLDR version.....
Make a backup, upgrade and save win 10 free upgrade, rollback or restore to previous operating system. At later time install win 10 for free with no time limit.