It's great to see you here today at planDisney, Samuel! There are so many magical experiences at Walt Disney World Resort, but dining inside
Cinderella Castle is definitely at the top of that list. I'm so excited to hear that you have scored reservations at
Cinderella's Royal Table for your family next week!
Magic Kingdom Park will be opening at 9:00 am on the day that you're planning to visit and that will give your family plenty of time to get through the gates and make your way up Main Street, U.S.A. to Cinderella Castle. Guests staying at Disney Resorts Collection Hotels do have
early entry to the Theme Parks, but that works a little differently at Magic Kingdom Park, which will be to your advantage. Cast Members typically open the gates for everyone a bit early, but only Resort Hotel guests will be allowed into Tomorrowland and Fantasyland before 9:00 am to ride attractions. So even though that 40-minute buffer should be plenty of time to get to where you need to go, if you arrive a bit earlier than that you may find that you'll be let in before the official opening.
I hope this answers your question, Samuel, and please let us know if there's anything else we can do to help you plan your magical vacation!
Jessica