Hi Jillian,
I'm glad you are making plans to get in every minute of
Walt Disney World fun that you can as quickly as you can after your arrival. You certainly can check all your luggage with baggage services until your room is ready. I've left suitcases, bags of food and open totes with no issues. I just wouldn't leave anything perishable.
If you are arriving early, I recommend that you do
online check-in and notify your resort of your arrival time. Sometimes your room can be ready on your arrival, even if it is early. I recently had a room be ready before 9 a.m. There's no guarantee, but it is always worth a try. There's even a spot on the online check-in form where you can let them know if having your room ready early takes priority over your other room requests.
Thanks for visiting the Disney Parks Moms Panel, Jillian. I hope that helps you make plans for your first day of your vacation. Please let us know if we can answer any other questions for you or make any recommendations for dining, attractions and more.
Enjoy!
Wilma