How long are new car salesmen kept at a base pay before they begin...

...receiving commission for cars they sell? A friend of mine began working at a local Volkswagon dealership about two weeks ago, and although he is still "in training," he has been selling at least one car consistently every day he's been there. He hasn't received any commission on any of the cars he's sold, and is being kept on a base pay that isn't much above minimum wage. How long should he expect to wait before he starts seeing actual money coming his way?