Hi ChiaChun and welcome to the Disney Parks Moms Panel!
I love that you would like to arrive at Disney's Magic Kingdom Park by
Ferryboat. When you arrive from a Walt Disney World Resort Hotel by motorcoach, you will be dropped off at the front of the park. The motorcoach drivers have routes they have to follow and they are not allowed to vary from their route.
However, you can still ride the Ferryboat. You can take a round trip over to the Transportation and Ticket Center and back to Magic Kingdom Park. Or, and I like this idea better, you could take the Monorail over to the Transportation and Ticket Center and ride the Ferryboat back over to the Magic Kingdom Park. You could always do this if you need a break during your day. I have friends who will ride the Monorail loop when they need a little rest!
ChiaChun, thank you for visiting us with your question. I hope you'll let us know if we can help you with any other questions!
Wishing you a magical vacation,
Amy H.