Any guesses? I think the SHB came out like 4 months before the Xpac. Maybe Feb or March?

I would assume it's close because people will also want to know if they need to upgrade their systems to get to a level a good performance in their set ups. I know min and recommended specs were released, however, you won't know you're happy with how the game is playing in your system until you get a chance to test it.