I think you are going to be close. I'm thinking the same thing. I think they will try to get most people in by Friday just to end all the ************ and moaning! Seriously though. The bulk of the pre-orders were in July. I'm thinking...
12/14 rest of July, Aug and couple weeks of Sept.
12/15 Rest of Sept - mid Nov.
12/16 Anyone else who pre-ordered before the 13th.
12/17 Everyone else.
They should have a very good idea in the next couple of days how many servers they are going to need. And they will see the stability. I wouldn't be surprised if they start really ramping up the invites.