So normally when my FLGS gets a wave of stuff, between pre-orders and 1st week pick-ups, it ends up selling about 80-90% of the inventory right away. I think it depends on HOW MANY of a ship people need.
The Tantive IV is still in stock - because not everyone needs one, and nobody really needs more than one unless they are collecting multiples (IE the special crew are all unique, so there really is no benefit to having 2).
Imperial Aces had a few left on the shelf - some bought 2, some bought only 1.
Rebel transport sold out instantly - since some decided to get 2, this was gone quickly.
I'm expecting the Z-95 to be the first to sell out, with the E-Wing to be the last one left in stock. Phantoms will sell out fairly quick, and defenders will probably only sell out 3rd due to the upgrade cards IMO. But I'd say Z-95's will easily be gone 1st week.
That concludes my predictions.