Hi there, Amy!
On September 02, 2012, the Magic Kingdom is scheduled to open at 9:00 AM, with Extra Magic Hours occurring that night after the Park closure.
Opening ceremonies take place every day at Park opening (and even if there are Extra Magic Hours in the morning for Resort Guests, the ceremony will take place when the Park opens to all Guests). You'll want to be in front of the turnstiles just a smidge before 9:00 AM for all of the festivities.
In order to get into the Park early, you will need a breakfast reservation (book 180 days in advance at [407] WDW-DINE or
online). You'll be able to get some nice shots on Main Street USA in front of Cinderella Castle (minus the crowds!), but most of the actual Park will be closed to Guests until 9:00 that morning.
You will need to have your breakfast reservation confirmation number with you when you arrive at the Park to enter before 9:00 AM.
Have a wonderful time!
See you later, celebrator,
-Deborah B.