This article says:"Beckham will make his Galaxy debut when the club hosts English Premier League power Chelsea in an exhibition. The English Super-Star will make his first appearance in a league game on August 5th when the Galaxy visit Toronto FC."
http://www.point-spreads.com/content/view/1919/2/
Here's the LA Galaxy schedule:
http://la.galaxy.mlsnet.com/schedule....jsp?team=t106