I just wonder if there are any ways to check the date and time when the Mac OS X was installed.
I guess the system must store the information of this type somewhere, but I don't know how to mine it.
In my case, my MacBook Pro was stolen. When I found it 10 days later, the hard disk had been repartitioned and it had been installed with a fresh Yosemite version.
Now that it turns out that if I know the time/date the Yosemite was installed, I may be able to identify who is the thief.