There can be all kinds of reasons for cancelling, so nobody can really say. Your odds of getting one are the same as anyone else's who checks. You also need to remember that at the time you are traveling, tables have been set aside for the Candlelight Processional packages. So your odds may not be as good as they would be any other time of year because there are fewer available tables for regular lunch reservations.
However, guests on a package resort reservation have to cancel the reservation more than 45 days out in order to avoid cancellation penalties, I think some assume that there could be some cancellations daily due to people backing out of their trips. Some check when it's 44 days from their own reservation just in case someone with the same check-in date might have decided to cancel.
Restaurants like Le Cellier have to be cancelled by the day before to avoid a penalty, so anyone who doesn't want to keep their reservation has until then to cancel. So look the day before and the day you want to dine.
All you can do is keep checking, as there's no way to know exactly when an individual might decide to cancel a reservation.