I have to agree with the others... it totally depends on the specific item.
However, with that said, my local Nordstrom counter seems to have stuff in stock a lot longer than some other places. I know they still had Madame B. stuff several weeks after the big ones - Metamorph and Moth Brown, were sold out elsewhere. Don't get me wrong, they did eventually sell out, but in comparison to like, the website and many other counters, they were as slow as molasses to sell out!
Same thing with Cockatease... I took my 6 B2M empties just a few weeks ago, after it had already sold out online, and never dreamed that I would be redeeming my empties for my very own pristine tube of Cockatease, but I did.
I don't know if it's a rumor or not, but I also read that some counters are limited in the number of e/s they will receive - especially, but not limited to d'bohemia e/s, so you might want to think about that too.
All in all... I know I'm just waiting for the stuff to hit online so I can place my order asap. I'm not going to wait on this collection!