Each to their own. As long as you're not hurting anybody, go for it. It's all about self control. I never tried any drugs (not including Sweet Ms. Mary) until I was 23 and felt I was mature enough to handle it.
A lot of my friends were on the pills and other shit from 15 onwards and some of their brains are permanently fried. It's sad to bump into an old high school friend that struggles to hold a normal conversation anymore.
As for weed, I love to indulge. My theory is its all good until it starts effecting your day to day life. If it gets in the way of friendships, relationships, careers or responsibilities, its not worth it. And that includes alcohol.