It was earlier than that; closer to 6:00 a.m. ET. The site can be a little dodgy at first. It will show the new dates, then not show them, then show them but not let you book, etc. I actually booked one set of tickets right at about 6:05 a.m. ET and then went to book a second set, only to have the site tell me that they weren't open for my dates (even though that date was earlier than the date I had just booked)!