Hi, Anisha!
What an exciting and magical Christmas Day for your family.
From my experience visiting Walt Disney World Resort during the holidays, my biggest and best tip for you is to be sure you arrive before Magic Kingdom Park opens. The earlier you get there, the more experiences you will be able to absorb before the crowd gets to the park. Eat breakfast super early and focus on enjoying the attractions you want to visit first.
When the crowd gets a little thicker, take the time to eat a lunch at one of the
Quick Service Restaurants. For your 8 and 6-year-old kids, they might have a great time playing
Sorcerors of the Magic Kingdom. It's one of my kids' favorite activities to play across the park and it doesn't require you to stand in many long lines.
If you want to enjoy a parade, I would recommend picking out a spot pretty early since there will be so many people around. It's a great excuse to slow down, sit on a curb, and enjoy a snack.
Have a very merry holiday!
-Jen