my question is can you take off a tempered glass screen protector off your phone and save it for a later time to use even if you've only had it on for like 3-4 days?
Not all products are the same. Depends on the protector and how you store it. Possible but unlikely to be like new when applied again. Also run risk of breaking glass when removing.
I did it. My wife got a 6s (upgraded from 6). I pulled the protector off the 6 and out it in the 6s. Granted, I wasn't particularly hopeful but I felt silly just throwing it out without at least trying.
So, if you're careful, it's doable. This was the zagg by the way.
It's been said it's possible; but 9 times out of 10, once a screen protector is installed then removed, it's pretty much rendered useless. Most of these things are a one-shot deal.
I've done this a few times with a Godosmith Ice Max 3D. Removed the screen protector and placed it on a clean lint roller sheet. Reapplied it a few weeks later and the only problem I had was that it took a bit longer for all the bubbles to disappear.