Howdy Sarah!
Great news! Yes...as long as your parents are on the reservation, they can check-in prior to your arrival.
Be sure to take advantage of online check-in prior to your arrival date. It will make their check-in quick and easy.
Disney's Old Key West Resort is one of our favorites! Your parents will have plenty to do until you arrive.
The villas are very spacious. If your villa is ready when your parents arrive, they might enjoy sitting on the balcony enjoying the beauty of Old Key West.
There are some great pools and a jogging trail if they are seeking to do something that is a bit more active.
They can also enjoy the shops and dining at Downtown Disney, which is a short water-taxi ride from the resort.
I'm so excited for you! I love travelling with my parents and/or in-laws. It adds even more magic to an already fabulous vacation.
Thanks so much for your question and please let me know if you need any further information.
Have a magical day!!!