Hi, Julie!
Your little princess is going to have such a wonderful time during her magical makeover at
Bibbidi Bobbidi Boutique!
There may be transportation available for you to get to Magic Kingdom in time for your reservation; however, transportation schedules change frequently at Walt Disney World, so I'd inquire about early morning buses at the front desk of Disney's All-Star Music Resort prior to the day of your appointment.
If you drive yourselves, I'd plan to leave at 7-7:15 a.m., so that you'll be sure to have parked the car, gotten over to the bag check area, found the line for Guests with early morning reservations and gotten into the park with plenty of time to spare. This will also enable you to get a great photo on Main Street, U.S.A., before the crowds start to roll in at Park Open.
Best to arrive with extra time, especially with so many gorgeous photo opportunities surrounding you in an uncrowded Magic Kingdom, Julie. ENJOY!
Send more questions as you think of them; we love to help!