Hi Erin!
What a great time to visit Walt Disney World Resort! Your toddler will have a magical time! I am not sure when you are planning on attending Mickey's Very Merry Christmas Party, so I can't offer a specific itinerary, however I can offer some tips on how to schedule your days to make the most of your Disney Time.
In terms of scheduling your days, you will need to visit the Magic Kingdom on the day you are headed to Cinderella's Royal Table. Other than that, I like to look at the
Park Hours and decide based on Extra Magic Hours where I plan on visiting each day. Extra Magic Hours are where a specific Theme Park opens early or closes late, and only guests staying at a Walt Disney World Resort are able to enjoy. It is a great way to enjoy the Theme Parks with less crowds and shorter wait times.
The day you are scheduled to go to Mickey's Very Merry Christmas Party, I would suggest visiting either Disney's Animal Kingdom or EPCOT during the day, as you will most likely be able to experience everything that your toddler will enjoy during that time frame.
If you have the Park Hopper Option on your Magic Your Way Base Tickets, I have found that being on the monorail, I enjoy heading to one Theme Parks during the day and finish off the day at Magic Kingdom Park. With little ones, it is so much easier to hop on the monorail instead of waiting for a bus back to your Disney Resort.
If you would like to send me another question with the dates you are attending Mickey's Very Merry Christmas Party, and specific interests of your toddler, I would be more than happy to provide you with a more specific itinerary for your upcoming trip.
Stephanie