I got an e-mail from Bitmain earlier this week. August 10, 5PM GMT+8 (so...5AM EST). Usually they don't send the e-mail until a few hours before the sale, but this time they sent it days ahead it seems. So tomorrow night, go to sleep early and set your alarm for a few minutes before 5AM, so you can login ahead of time as CryptoCrane mentioned.

To get on the mailing list, I'm pretty sure I had to bug them to add me by submitting support tickets regarding ordering.