Hi there, Sabrina!
Making Advance Dining Reservations (ADRs) at Walt Disney World can be a daily activity as you change your restaurants, itinerary, and so on. And yes, there can definitely be times when it feels like there is no hope of getting that coveted spot at Le Cellier or Chef Mickey's.
The window for making reservations opens 180 days prior to a Guest's check-in date. Many Resort Guests definitely take advantage of this, and make reservations as soon as that 180-day mark is reached.
But this should by no means be disheartening. While it's unclear if tables are "held back" and released periodically over time, there is quite a bit of turnover on a daily basis. Guests often make dining changes that necessitate them to cancel one reservation in order at make another; this is particularly true now that Disney has instituted its new cancellation policy, wherein a penalty is assessed by anyone on a reservation that is not cancelled in advance of the reservation time (check each restaurant for specific details).
You'll want to check at least twice daily: once in the morning and once at night. You can call (407) WDW-DINE or visit the
reservation center online. I tend to call the Cast Members directly, since it seems that they have a quicker, all-access pass to seeing what's available.
But do not get discouraged. You're going to be successful in many of your reservation quests, and I'm sure you won't be disappointed with your alternates.
Have a wonderful - and delicious! - time!
See you later, celebrator,
-Deborah B.