Hello, Christina!
Welcome to planDisney! We are so excited to answer your question and help you plan your MAGICAL Walt Disney World vacation! It looks like you are going to arrive in a few weeks! WOO HOO! I am counting down the days with you!
First of all, I am soooo proud of you for getting your
Disney Theme Park Tickets and reservations in advance! Way to go! Now, you have asked a great question about the Park Hopper Option and getting into a Disney Theme Park if a park has reached capacity. Based on my research and what I have heard from other guests, I believe you will be able to use your Park Hopper Option even if all four Disney Theme Parks do not have reservations for that particular day.
Now, I do have a recommendation for you! In order to check the availability of your second Disney Theme Park, I would recommend calling The Walt Disney World Park Hopping capacity hotline at (407) 560-5000. That way you can be sure you will be able to continue the MAGIC in the second Disney Theme Park you choose to visit.
I am wishing upon a star you will have no problems at all using your Park Hopper Option! (I honestly think you will be good to go!!!) If you have other questions, please do not hesitate to ask! We are here to help in any way!
Have a MAGICAL day!
Wes