prgr,
Most people will receive a notification from every school they applied to on Dec. 1. It may say you are accepted, rejected, or still being considered. Rolling admissions means they review applications in the order they are received, and many times will start accepting people in that order as well. This is not an exact science however. The person that applies two months later will likely have a harder time getting in on Dec. 1 but may have no problem getting in in January. It's different for every school....there is an advantage to applying early, but not a huge factor overall.