That's what usually happens, but I haven't heard anything one way or the other, so far.
The other usual thing that happens is that the more popular models go to back order within hours, if not minutes. And it's pure luck if your order gets through.
Even though Apple beefs up the supply chain and order system every year, demand seems to stay ahead of their ability to cope with it.
Tablet demand, in general, seems to be waining, so maybe this year will be different.
But I doubt it.