How to find which was first window installed on my system?

First windows is when you first bought your computer. If you had windows 8 pro but upgraded it to windows 10, you can find windows 8 pro in system settings under system restore. It will bring up a menu saying which windows you want to use (something like that) it will show windows 8 pro and windows 10. Exit system reboot so that you don't accidentally reinstall 8 pro again. I am a computer expert but havent messed with a computer in awhile now. My tablet is my form of computer. I like windows 10.