gthang:
Welcome to The Gym! There's really no telling how soon you will see results. Some men gain within a few days . . . . Others, unfortunately, never gain.
It also depends on what you're trying to gain. A lot of men gain extra hardness first and then extra inches later.
If you want to gain the most amount possible, don't rust it. Take it slow at first, get plenty of rest, and gradually increase the intensity as time goes on.