I'm 16 and i do it often with friends, gf, anyone who is down to toke. Personally, i had the chance to start marijuana when i was like 13-14 but i didn't cause i wanted to grow and learn more about the stuff before i did it a bit more than what i had. I waited a few years and now i'm glad i did. It won't fuck you up in school.. believe me. Just don't do it before school or after school when you have homework to do. Concentrate on school and do it on the weekends. believe me, everything will work out then.