You might be able to tell just by some of the dates on certain files. But it appears if you look in the Windows\Panther directory on the SSD, there is a setupact.log. Open that and see what dates are shown on the left side. This is probably your install date.
Need any help with booting to the SSD? More info, like how you installed Windows 7, and what other drives were on the system at the time. A Disk Management picture (including graphical partition info) taken with the snipping tool and attached with the paperclip on Advanced Replies might help.