Howdy, Amanda!
Welcome to the Disney Parks Moms Panel and thank you for sending us your question. We are always here to help you plan an unforgettable Walt Disney World Resort vacation.
Halloween and Christmas decorations normally start to go up at the Magic Kingdom Park in preparation of
Mickey's Not-So-Scary Halloween Party and
Mickey's Very Merry Christmas Party. The 2016 Party dates have not yet been announced, but you can continue to check the official Party pages and the Disney Parks Blog for more information as we approach the 2016 holiday season.
Last year's Mickey's Not-So-Scary Halloween Party ran from September 15 - November 1, 2015. Mickey's Very Merry Christmas Party ran from November 8 - December 18, 2015. It appears that there is usually one week between the end of the Halloween Party and the beginning of the Christmas Party. Decorations normally go up throughout that week to be completed in time for the first Christmas Party.
I suggest that you continue to check the official pages for Party dates and schedules and that you plan to visit Walt Disney World Resort for a minimum of 1 week if you wish to see Halloween and Christmas decorations at Magic Kingdom Park.
Amanda, I hope that I have answered your question and that you will return to the Disney Parks Moms Panel if you have any other inquiries while planning your vacation.
Quick Tip: Check out the official
Holiday Events and Celebrations Walt Disney World Resort page for information on holiday attractions, events and dining!
Wishing You a Magical Vacation,
Priscila