Hi Lori, You'll be cutting it very close. I'm afraid you'll need to take a cab, as the buses will take way too long. When you factor in the walk from Cinderella Castle to the front of the Park, the bus ride over and the jaunt from the entrance to Downtown Disney over to the World of Disney Store...that will be at least an hour travel time.
Breakfast at Cinderella's Royal Table is so enchanting and such a
special experience, you won't want to rush out of there. I'd hate to
have you end up so stressed about making your reservation that you don't
thoroughly enjoy your meal. Have you considered making reservations at the Magic Kingdom location of
Bibbidi Bobbidi Boutique instead?
You could see about booking an 8:00am reservation there and having your little girl transformed
before breakfast. You could also wait until later in the day and not have to leave the Park. If neither of these is an option for you, then I would recommend moving your Downtown Disney location reservation to a later time instead.
Have a wonderful vacation,
Kaylene