20 was the year I gained the most lean mass in my life, no steroids at all. Your test is super high, and in my case 20 was the year my diet came together. I instituted a structured meal plan and I exploded.
I won't preach about waiting till your natural test is on it's deathbed because I'm only 22, which is also why you should listen to me as I can relate easily to you. WAIT for atleast 2 more years to be safe. Starting test now is a waste of money and too much of a risk. Common theories suggest you are still developing from boy to man until age 21, and leaving a buffer year to 22 would be wise to make certain your gonna be okay.
http://www.youtube.com/watch?v=8rIiY...eature=related
that link is about teens but definately applies to 20 yr olds, do you think you changed that much over that one day when you turned 20? hell no
And when you are 22, 23... you can benefit from a single compound at low dose because you still have lots of natural test. I've heard lots of people getting huge gains on test E at 300mgs and retaining them at my age. Many "old" people you see using stacks or ridiculous doses do so because they have to compensate for the lack of natural test.
It comes down to waiting untill your done puberty, as embarassing as it sounds its true... and many males don't fully mature until as late as 21. Just because your balls dropped and your voice stopped squeaky is no indication that you are mature.
It was hard for me too, but sit on your hands and develop your training and diet... (and get your head out of your @$$ there is always room for improvement) and once that is done and you do add AAS the combo will take you further than you ever would have gone starting anabolics now.