When are the 20 free songs for Rock Band 2 goina arrive?

[Coca-Cola]

thanks to this thread I just got the code for the 20 songs.
i didn't even know about it.

But please somebody tell me where is the "Redeem Code" button in NXE.
The website simply says to go to Xbox Live Marketplace and press "Redeem Code" button, but I can't find it anywhere.