xlovely, it really is hard to tell. I went to the South Coast Plaza location. While I absolutely adore Lanvin, I myself haven't heard of it until only 2 years at best, while Jimmy Choo I heard of when I was a lot younger. IMO, Choo is a lot more "mainstream" in a sense that resellers/non enthusiasts would be quick to capitalize on events such as that, and may not jump so much on Lanvin.
So, when I went to the Choo event, I got there around 4 a.m....and there was enough for me to get one of each, although I only ended up with 1. I think you'll have a better chance with Lanvin, but I don't want to be responsible for you if you show up at 6 a.m. and assed out =T