Yay!!!! mimi what day do you recommend going?
Well, of course the best time/day to go is the earliest day/time you possibly can

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If it will be anything like the last sample sale, there are lots of racks of DVF goodies organized by size. There are also boxes full of samples and stuff all jammed together. Oh, and don't arrive near closing time, because you won't have enough time to try everything on.
The dressing room--It's like you're a herd of cattle. You will have to fall in a very long line, where they admit 10-15 girls into the dressing room at one time. It's an open dressing room, so best not be shy! Wear a cami so you don't have to deal with your bra. There's no limit to how many clothes you can bring in (I think), but you only have 10 minutes to try on everything you bring in, so you have to be quick. Once the 10 minutes is up, you'll get kicked out.
My best tip would be to scope out your local DVF boutique and try on several different pieces for size, so you have a rough idea of what your DVF size is and how it will fit you, just in case you don't make it to the dressing room.
Hmm...even though I'm on a self-imposed shopping ban, thinking of this sale is really enticing me to go!!
do you think they'll have size 0's??
Yes, they had a lot of size 0 there, the last time I went.