Hi Jennifer, If you booked an appointment at the Downtown Disney
Bibbidi Bobbidi Boutique location for 9:00am, you
should be OK. It takes an average of 30-60 minutes depending on which package you choose. Factor in that you might not get seated right away, your daughter may take her time choosing, and other unforeseen things that can eat up your time (like photos). Hopefully you'd be leaving Downtown Disney by 10:30 or so. You need to plan on checking in at the podium for Cinderella's Royal Table by 12:05. The castle is at the end of Main Street, so give yourself 15-20 minutes from the gate to get to the castle. You need to be at the front gate of the Magic Kingdom by 11:45 at the latest. In theory, a 9:00am appointment
should give you plenty of time. However, I like to play things on the safe side when dealing with transportation that is out of my hands. In other words, you can't control when the buses will come, and you'll need to get on a bus to a Resort from Downtown Disney first and then transfer to the Magic Kingdom. You could take one to the Contemporary or the Polynesian and then jump on the monorail to the Magic Kingdom (or walk from the Contemporary). Either way, these are things take time. I personally would book Bibbidi Bobbidi Boutique inside Cinderella's Castle instead. This way you aren't stressed and worried about time, and you can simply enjoy watching your little girl be transformed into a Princess instead. It is
such an enchanting experience, one that my little girls thoroughly enjoy!
Hope this helps and that you have a wonderful vacation!
Kaylene