Don't know when it opened up ... but got mine..9:23am (Friday May 2, Mouse time)
Made mine for June 22nd
Good Luck...
Scott
Edit: went back in at 9:35 am to book the 26th also.. (just in case of weather or unforeseen trouble)... I'm getting error messages about system trouble... I'm guessing it's getting very busy as word spreads....
Edit-2: After trial and error (messages) got back in at 9:50 and booked a second day the 26th Hope this helps..