Hi, Kelly, and thank you for stopping by with your question! Magic Kingdom Park is truly an enchanting place and I love being there any time of year. However, my favorite time of year to visit in during the fall, when it takes on a spooktacular mood. My daughters, however, think the holiday season is the best with all the very merry decorations and festivities.
Magic Kingdom Park does tend make its seasonal transformation as soon as the last
Mickey's Not-So-Scary Halloween Party concludes. This year, the last one will be held on October 31, 2018, and the first Mickey's Very Merry Christmas Party is on November 8, 2018.
The decorations are swapped out pretty quickly; most are done overnight! If you plan to visit the first couple of days of November, you may be able to see the fall decorations. I expect the change will happen sometime within those first few days, so I hope you do arrive sooner, rather than later that week.
In my experience, the other Walt Disney World Resort theme parks do not make the holiday transition as quickly.
Epcot will still be celebrating its International Food & Wine Festival during the first few weeks of November, and I highly recommend hopping over there to check it out. You can explore the delicious Global Marketplaces, dance along with some great bands, and even attend some food and beverage seminars hosted by renowned chefs.
I hope you have a magical visit this fall and please let us know if we can answer any other questions for you!
Brandy