Hi,
About timed pubertal changes in boys, refer the following link:
http://en.wikipedia.org/wiki/Puberty
Adolescence, which includes pubertal changes, also is a period of development and maturation of the emotional part of the brain, which makes the boys in their teens look most problematic to their parents. You can read more about this from the following article :
http://www.guardian.co.uk/science/2005/mar/03/1
Solace
I remember exactly when I reached puberty. I was 13, and I began to have warm, sexy feelings a while before I began having wet dreams. I discovered in the playground at recess that if I climbed on the parallel bars and let myself hang loose, I could induce that warm, sexy feeling. About 3 or 4 months later, when I would hang from the parallel bars, I had my first wet dream. As the months progress, my voice got a little deeper and I noticed that I walked more manly. The sexual tension increased so much, that I had to masturbate about three times a day. The bathroom was the only room in my house that had a lock, so I found a lot of excuses to use the bathroom. My parents and brothers and sisters knew what I was doing, but the bathroom held all the secrets, and no one bugged me.
Puberty begins and continues until you cannot have sex any longer, like until you become an old man like me. Expect some facial changes, but the changes are not big enough for you to worry about now.
Have a good life and take care of your health. I am 75, and I am still sexually active, although I do not look for sex. Remember, it is your brain that gives you sexual pleasure. Your penis is only an instrument that takes orders from your brain.
Harrald