I prefer not holding or dealing with an operator who has no real vested interest in getting me what I want, and I hate having to say "can you check this time, or this time or this day or that day?" and feel pretty computer saavy, so I think I would check around 7AM ET every morning, isnt that when the best chance is for something being cancelled?
I will also have fun when my time comes to mess with my reservations looking as often and when I want to, without calling all the time.
That being said, DH and I plan to be on the computer and phone on Oct 27th, since it will be soooo dang busy with people being able to make reservations 180 days out.. argh.. our 90 would have been Nov 2nd and only would have been competing with other Feb disers for Operator attention!