diverman - 6:53 am on Feb 2, 2006 (gmt 0)
In my case, the ads seemed to be pretty accurate right away. There were some RON ads, but they were gone within a few hours. Also, I rotate between YPN and AS, so it could help "train" YPN on your pages if you can get some form of % rotation (ie. giving YPN 5% of page loads).