Our family is traveling to Florida for a family reunion and the NASCAR race over the 4th of July holiday. We have ONE day for WDW, and because I have 10 and 11 year old daughters, I determined Magic Kingdom is the best choice for us since we must see princesses. I had no idea you could book attractions through Fast Pass before arriving at the park. We were planning to purchase tickets upon arrival, and then try to Fast Pass two or three attractions that we really want to do... particularly the Seven Dwarfs Mine Train, Splash Mountain, and Big Thunder Mountain Railroad. Is it possible that these attractions would be completely pre-booked and hence not available to the guest who did no pre-planning? I want this day to be the best it can be for us since this is probably our "once-in-a-lifetime" trip to WDW, but both my daughters have ADHD and one has a sensory processing disorder, and I don't want to stress everyone out, pushing them on to the next attraction so we get to see everything. I'd appreciate any advice or even redirection to another place in the forums that may have some ideas for us. Thank you!