Maybe you shouldnt do it at all. Dont be dumb!! You're running a huge risk of f'ing yourself up...for life. Think about it, really think about it, do you want to be on TRT for the rest of your life, say the next 55-60yrs? Oh, it sounds great, test forever, YAY. But what happens if you lose interest in weights, get married and want to start a family just to find out you may be sterile. Wait until your 25, please!