Hi Lisa!
I can tell from your question that you're the kind of gal who likes to squeeze every magical minute out of your vacation. Me too! You most certainly may head to one of the Disney theme parks prior to check-in on your arrival day. In fact, you're welcome to leave your bags with Bell Services at the Walt Disney World Resort hotel you'll be staying at. They'll keep your belongings safe while you are having fun elsewhere on property. You can either claim your bags when you return to your hotel after having a day of fun in the theme parks, or they can deliver them to your room after you check in.
The day you check out works similarly. If you wish to spend a full day at the theme parks that day, no problem. Once again, you may leave your suitcases with Bell Services while you enjoy rides and attractions to your heart's content. Just stop by and present your claim check to pick them up before you head home. This is just one of the
perks available to Guests who will be staying at a Walt Disney World Resort hotel during their vacation.
Don't hesitate to ask additional questions as you plan your vacation. My friends and I here at the Disney Parks Moms Panel would be happy to provide any information that you may find useful.
Sending best wishes and pixie dust,
Jill