NOTICE REGARDING THE USCF RATINGS SUPPLEMENT
The USCF publishes official ratings updates (known as "ratings supplements") on a monthly basis. These supplements now reflect tournament results received by the third Friday of the previous month. For example, the November 2012 supplement should reflect results received by October 19, 2012.
In tournaments, player's ratings are used to determine pairing order, eligibility for some of the prizes, and for correct section placement.
In order to utilize the most up-to-date official information, it will be the policy of the NSCF to attempt to use, at pre-entry time, the following month's supplement for any tournament that is run on the final weekend of any month, assuming availability for download.
You may see a more detailed explanation at The Rating to Use.