Heigh ho, heigh ho, it's off to plan we go, Natalie! Starting our day at Magic Kingdom Park with a delicious breakfast at the Beast's Castle is a favorite of mine. They have so many wonderful offerings, but I find enjoying the Open-Faced Bacon and Egg Sandwich is a great way to make it from Fantasyland to Adventureland and even Tomorrowland before needing another bite.
A pre-park opening Advance Dining Reservation in the park has sometimes been a great idea for getting a jump on the crowds. The Cast Members do occasionally let breakfast attendees line up near Seven Dwarfs Mine Train once their breakfast is complete. As the park officially opens, those lined up can possibly enjoy a short walk over to the attraction to get at least one good ride in before other guests reach the attraction's queue. While I have recently experienced some days that this has happened, sometimes this line has been held and then mixed in with the incoming crowd.
Natalie, if your main focus is to get to Seven Dwarfs Mine Train, I would recommend that you try to get an earlier Advance Dining Reservation or just cancel it, choosing another way to get to the mine. The 8:45 a.m.time puts you way too close to the 9 a.m. park opening to be able to enjoy your breakfast and make it out of Be Our Guest Restaurant in time. You should also consider
Early Morning Magic in Magic Kingdom Park, which features pre-park opening access to not only Seven Dwarfs Mine Train, but also The Many Adventures of Winnie the Pooh, Princess Fairytale Hall, “it’s a small world,” Mad Tea Party, and Under the Sea – Journey of the Little Mermaid. To me, this separately ticketed event is a much better value for families and even includes breakfast!
Thanks for stopping by and please let us know if you have any other questions!
Brandy