I'm 15, and just decided to try masturbating. I did it, and everything "came out" (figuratively speaking) just fine.

If I do this 2-4 times a week, about how long until I see growth changes coming into effect?
- age 15, Illinois

What growth changes? Masturbation does not affect growth of your body, or any part thereof, either way. Assuming you're still going through puberty, you and your penis will grow at the same rate no matter how much or how little you masturbate.