[sogen]

Actually what really happens is that store managers have to decide what to stock in May, seven months before Xmas.

Source: I was manager at a large store.

[oneeyedpigeon]

The NES classic was announced in July, though. Would retailers have been given some advance notice under an NDA, or is this an exception?

[sogen]

The retailers are flown to this place and treated like kids in a candy store, so they need to interact, feel, and try all new products, because a bad investment in inventory (too low or too high) will affect the store.

My best guess is that they are shown a working prototype, but for a company this huge (and protective) I don't know.