Our last few trips have involved very early flights, young kids and early arrivals, where we typically arrive to the resort between 10-11am.
What I do is pack one carry-on back pack to use as a park bag. In it, I pack a change of clothes for the family, bathing suits, toiletries to refresh in the lobby bathroom, and sunscreen along with whatever other necessities we need. We get to the lobby, check in physically at the front desk so they know we're there, and leave our bags with the hotel to store. Freshen up in the lobby bathroom and then head to a park, usually stopping for a snack or a small lunch along the way. I make sure to have a lunch reservation around 1-2, because by then it's hot, we are tired from getting up early and travel, and it's nice to have an air conditioned place to sit and relax while you wait for the room to be ready. Usually our room is ready by the time that meal ends, but if not we can always head back to the resort and hang at the pool a little until room is ready. I don't usually do dinner reservations for that evening, because I just like to see how we feel and be able to turn in early if we're tired.
With where you're staying, and because you don't have any little kids, you could easily just hang at the pool in the morning, go to Disney Springs to putz around and for the lunch reservation, and use your time that way instead. Just make sure you have your pool/park essentials in an easy to access bag so you're not rooting through your luggage for your bathing suit in the resort lobby
