Just a little conservative theory that I've come up with from personal stats.

Anyone who's studied business/probability is probably aware of this bell graph.
Innovators: 2.5%
Early Adopters: 13.5%
Early Minority: 15%
Early Majority: 19%
Late Majority: 19%
Late Minority: 15%
Laggards: 16.5%

Notice how it's split into 7 nicely?
Anyway, I have 6 guild members/friends who ordered the day the game was available, so that puts them around the 100k mark. My cousin ordered this fast as well, so he's in the top 100k. They all got into the 1st wave.
My girlfriend pre-ordered 1 for me on 25 July. I checked VGchartz, during that week, there were 45k pre-orders already week ending 30 July. I got into the last wave.
Last week there were 900k pre-orders. If what is said about 2 million so far being sold is true, 2.5% of 2 mill is 40k.
By my estimate, the early guys are those who got in today are in that 2.5%. If everyone looked up the week they pre-ordered, and do some simple math, you'll know what percentage you're in, and can pretty much guesstimate the day you'll get early access.
Of course, this is all theory but I'm waiting on some guild members on WoW to tell me when they ordered. My girlfriend ordered hers on 26 September, that week there were 450k pre-orders. So i'm gboing to guess she'll only get in on Thursday/Friday morning for me. Just a little theory because this is how product diffussion works, and if BW are business-savvy, they'll probably be going off this sort of scale as well.