Sara,
Thanks for asking your question to planDisney!
Disney does not publicize a specific time frame for how far in advance that they post park hours. But in my experience of late the hours have typically been getting posted in the range of 60 to 75 days beforehand. Because they post them in batches, it can vary, naturally.
As an example, on the day I am writing this response they have the next 72 days of park hours posted.
RECOMMENDATIONI strongly recommend that you make
theme park reservations right away. I understand the desire to wait for park hours so you can plan out your vacation days. But you really want to lock in at least one park per day now. You can change your park selections later if you want to. The park you change to would have to still have availability, but assuming it does you will just cancel the initial park reservation before making your updated choice. This way you don't get completely locked out of all parks on a planned park day.
BONUS TIPI just checked the
Disney Park Pass Availability Calendar for the week you are here, and all parks are still currently available!
Write me back if you have any follow-up questions.
Have a Magical Vacation!
Doug