Senior Online Community Manager Stephen Reid posted on the official forums (which are back up, by the way) about how the waves of access to the game. You are ordered according to when you input the preorder code, not when you actually preordered the game so unfortunately, if you were one of those first people to preorder but didn’t input your code right away, this will affect the order in which you get in. 1n5b4p
Anyway, everyone will be granted access in the order in which they redeemed their codes, and in batches of waves. So there were two waves that went out early today. My friend got in at 7am his time this morning. No one can tell us specifically when we will each get our invite but the waves will continue to go out until everyone who preordered gets in.
In the thread, Reid explains why they will not allow more people access at one time:
For us, servers, to maintain all server types, and to keep queuing to a minimum (although we expect that to happen as we head towards December 20th). So far, all that has been successful for us on Day One.
See you in the game soon!