Hi Tanya! Welcome to the Disney Parks Moms Panel.
Glad to hear you will be visiting WDW in December. Holiday Season brings an extra charm to Disney Parks with its beautiful decoration. You will have an amazing experience.
It is very easy to move with a stroller at Disney World. To arrive at
Magic Kingdom Park you will drive to TTC (Transportation and Ticket Center) and from there you will take the monorail or ferryboat to access the Park entrance. From your car to monorail and ferryboat boarding areas, you need to take a parking lot tram and this is the only moment you need to fold up your stroller. Once you disembark, you can unfold it and take either the monorail or ferryboat.
I encourage you to try both experiences. I usually take the monorail to go to Magic Kingdom Park in the morning, and the ferryboat to return to TTC.
Hope this helps your planning. Please, come back to visit us again if you have further questions.
Have a magical day!
Gina V.