Welcome to the Disney Parks Moms Panel, Shawn!
You're in for a festive treat during
Mickey's Very Merry Christmas Party, one of my family's favorite seasonal events.
You'll be able to attend this yuletide party using your Mickey's Very Merry Christmas Party Ticket beginning as early as 4:00pm on your designated party night. Be sure to look for the specially-marked entrance for Guests who are heading into Magic Kingdom Park for the party. Cast Members will be stationed just past the touch points to provide you with the required party wristband. The party itself will not use up one of your 3-day Park Hopper Passes.
However, should you choose to enjoy the day at Magic Kingdom, or enter the park prior to the 4:00pm early entry time for party guests, you will need to use one of your regular admission days. My family loves to have a "resort day" during the day, a late lunch at a Monorail Resort dining location, and then head to Magic Kingdom for the 4:00pm early entry for party guests. This strategy allows us to rest and refuel before trying our hardest to make it to midnight while saving our Park Hopper Passes to schedule around our Mickey's Very Merry Christmas Party night.
I hope this helps answer your question, Shawn! Please let me know if you should have any additional questions. I am here to help.
Happiest of Disney Holidays!
Faith