Once you add the codes to your steam account, you can install and uninstall the games at your leisure.
e.g. add the codes to steam, and install SR3 in the new year. sorted!
btw just saw this in small print ......
Steam will not provide extra giftable copies of games you already own

if i click on teh "redeem key" option does that mean its stuck with me or can i key the key and gift it at a later date ?
The key is just displayed on the webpage. It doesn't link to Steam until you redeem the key inside Steam itself. So you can just give the recipient the code for them to redeem at their leisure.

