To be fair, I'm not surprised that the OTA hasn't arrived yet, considering Sprint hasn't even received theirs. I suspect it has to do with a few bugs found within those from MM builds already release as well as the 3.8 kernel exploit which has already been patched and just needs to be implemented to the US carrier roms. Moversi hasn't tweeted on a delay for the T-Mobile release though so I don't know what's going on for sure.
All we can really do is hope that the rollout happens soon and constantly check the software update section in settings.
Cynicism Evolved