There's no specific dates for those. They just basically announce when one's on the way and the rest is history.
They haven't had one in awhile and from a business perspective it's probably better off that way. Sales can be a double edged sword as they allow you to move product, but then it can also prevent people from paying full price on things in the first place if they think that they can get it for less down the road.
I don't think we'll see the type of stuff that we did last year around Black Friday etc. for that very reason. All it would do is set a really bad trend. Not for *you* but for *them.*