Hi Melanie,
I love to see that you're planning so far in advance! You've come to the right place, as
I believe that planning is half the fun!
That 180-day point ahead of time is really important for planning purposes. It's the magical day that
advanced dining reservations become available, and it's also the day that
Park Hours are released, although they are always subject to change. And yes, if you already have a reservation at a Disney Resort hotel, you'll be able to make advanced dining reservations for the entire length of your stay, up to ten days, at that 180-day point, which is a great perk! So you are correct that you won't be able to know for sure what time the theme parks are open for each day of your vacation when it's time to make all of your advanced dining reservations.
However, don't worry. I have some suggestions for you. At that 180-day point, I simply go ahead and make
dining selections for our entire trip, even without knowing for sure what the Park Hours will be. Then as each day's hours are released, I make any changes to my reservations, if necessary. I've always had luck getting the times and restaurants that work best for my family. There are, however, a few restaurants for which advanced dining reservations fill up really quickly. I'd encourage you that if you are able to get a really popular reservation at that 180-day point, you may want to consider keeping that regardless of what the park hours end up being and work your trip around that special meal.
I'm sending some pixie dust that you'll be able to find the perfect advanced dining reservations for your family! I hope you have a truly magical...and delicious...vacation, Melanie!
Missy