well everyone is different...generally, it is said that anything more tahn 5 pounds of pure muscle per year is uncommon...now if you just started lifitng, then you may gain siginificantly more in a year if you are consistient...and 5 pounds of PURE muscle is a lot...
as far as speeding it up...adequate rest/diet, etc...creatine will probably help you build mass...although i wouldnt recommend it if you are under 18 and still growing. stay away from anything that you think might be dangerous...