Hi Sarah,
Welcome to the Disney Parks Moms Panel! I just faced a similar dilemma. We now plan our park strategy without knowing the park hours with absolute certainty.
I check the
park hours for a few weeks prior to my dates. So, if we are traveling on a Sunday through Saturday, I check Sunday through Saturday at least two weeks prior to the dates of our visit, paying particular attention to park opening and
Extra Magic Hours. Although we no longer do Extra Magic Hours, we do love pre-park opening dining reservations so that we can enter the parks before most other guests. We have to make those pre-park opening dining reservations on days when a park does not have Extra Magic Hours so that we can enjoy the magical feel of an almost empty park as we walk to the restaurant.
My family now prefers to visit Magic Kingdom on our first day and last day. Then we pick the order of parks in between. I go ahead and make dining reservations based on that plan. Occasionally, I have changed plans. It is possible. Just keep in mind that some restaurants get booked quickly and it may not be easy to change the reservation.
Cinderella's Royal Table and
Be Our Guest are two restaurants that may not have availability if you try to modify them, but I have been persistent in the past and have managed to change dining times at those restaurants.
Sarah, I am sending pixie dust your way hoping that you are able to make those dining reservations!
Magic, memories and Minnie Mouse hugs,
Donyell