How do I use Double XP Codes?

I don’t know if I should use it now, or use it later, because I think if I use it now, the day will go and it will be wasted. Then again, if I use it when Halo 4 is launched, the double XP thing will have expired and I have a useless code.

Just enter in the codes and don’t apply them until you want to use them. As long as you apply them before January 31, 2013 (I think) you should be fine.

Go to Dewxp.com, make an account, then input your codes. You can redeem them by linking them to your xbox live profile.

I’ll use it when Halo 4 drops just to be on the safe side.