I can't speak for AA/USAir with absolute authority, but I believe they still allow the same early check-in.

JB will not allow the same early check-in, or at least wouldn't allow it on a Saturday in early December. They went strictly by the book and said it was because of inadequate space for the accepted luggage. I know this because the previous year we called the SXM airport and were given misinformation regarding JBs policy and arrived at the airport expecting to be able to check in and get rid of our luggage according to what they had told us. We ended up having to sit and wait for an hour and a half to get rid of it even though they had checked us in and already given us our boarding passes. <img src="http://www.traveltalkonline.com/forums/images/graemlins/handshake.gif" alt="" /> <img src="http://www.traveltalkonline.com/forums/images/graemlins/handshake.gif" alt="" />