Hello Jillian,
Welcome to planDisney! Thanks for visiting us with your question. Your magical vacation is just around the riverbend!
Disney bus transportation from All-Star Music to Magic Kingdom typically starts around 45 minutes prior to the start of
Early Theme Park Entry. For the December date you mentioned, Early Entry would begin at 8:30 AM, so the buses would start at 7:45 AM. Unfortunately, this won't be early enough for you to utilize a Disney bus to arrive at Chef Mickey's in time for your reservation.
If you will not have a personal vehicle to drive, your next best option would be to use a ride share service like Uber or Lyft. I've found the rates using these services from one Walt Disney World Resort location to another is quite reasonably priced. It's also nice to be able to control your exact pick up time.
Although a tad more expensive,
booking a Minnie Van ride is also a really fun, pixie-dusted option! These vans are incredibly comfortable, can offer car seats for any littles, and even provide Disney entertainment on small screens during your journey.
The festive party at
Chef Mickey's is hard to beat when it comes to fun character dining experiences. I have not yet experienced the breakfast buffet here, but bravo on getting your day started so early. If you plan to spend the day at Magic Kingdom afterwards, the quickest option to get there after Chef Mickey's will actually be to walk from the Contemporary Resort right to the park entrance. You should be there in time for rope drop, and beating those later morning crowds. Woo hoo!
Jillian, please enjoy every magical moment of your amazing visit to Disney World! I hope this helps. Please feel free to send any other questions to planDisney... we'd be happy to assist.
See ya' real soon!
Tami