Dec 1st is an approximate date. Some schools mail out acceptances on Dec 1st so you won't get it till a few days later. The closer you live to the school the faster you will get the mail. Some schools mail out acceptances in anticipation of you receiving it Dec 1st. In that case you can actually get the mail before Dec 1st, on, or after as well. The range is pretty much from Nov 28th - Dec 6th. If you still haven't heard from your school outside this range the mail was either lost or you haven't been accepted as of yet.