All of the rebirth deluxes so far have been after the standard paperback collections are released. That seems to be the case too with Snyder's Justice League, which has a deluxe Edition listed for December this year.
If Morrison's GL is getting a deluxe edition (and it's as good a candidate as any), it will probably be after the paperback editions of the standard HCs are released. If I had to guess, I'd say the first deluxe would be about 18months after the first standard HC, but that's making a lot of assumptions.