I need a lil help here!?!

Okay, so im with at&t. I know that sprint they make it where you are eligable for your new contract two months before the actual date. Do you know if At&t is this way? like say my contract was up in march. Could I actually get a new phone in January? some companys are this way. Just not sure about At&t. if you know please tell me it would help alot! thanks! :)