http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=b56f8fa29935f010VgnVCM1000000ecd190aRCRD&vgnextchannel=b328194d3e88d010VgnVCM10000048f3d6a1RCRD
But in DOS' visa bulletin, it sez your date must be "earlier" than the listed date.