If you're really freaking out, you might want to consider asking them to get them in a little earlier than you originally asked. It was making me SO anxious to wait that I politely told my recommenders I was worried about getting my stuff in early, and none of them had a problem with it. You also might want to have them fax their letters to LSAC, since it usually gets processed within a day. Be careful with this, though, since several of mine got lost this way and had to be re-faxed later.