I will be buying a Wii black system brand new from Amazon as a Christmas gift and wanted to know if it was possible to wait until then to register it instead of losing a couple months of warranty (because it would still be in the box until Christmas)

I called Amazon and they said they do not automatically register it like when buying it at a store, like Best Buy, etc.

As far as registration goes, How would Nintendo know that I got it in October and not December ?