From TOR community manager
Today (yesterday), we invited people who had pre-ordered up to the very beginning of October (roughly). Tomorrow (today), we're going to be inviting the same number of people again; that will take us up to the last week or so of November. On Friday, we'll be inviting even more, and we'll give you an update on that tomorrow.
I should get in today in wave 2 or 3 since I pre-ordered the game at the end of October.