Clearly theres no talking this guy out of it...
By 07 youll be 20, maybe well on your way to 21 so wait until then if anything. Get a good strength base going, and keep up your cardio and sparring so you dont lose mobility (personal experience). Clearly your looking for an edge (whether legitimate or not lol) on your opponent, so your might want your cycle to be peaking right around fight time. Popular drugs amoung mma guys/ boxers are things that will give you lean mean, and not bloat you.
ex, Anavar ... safest, easy on system, etc
Winny ... lean gains, stronger sides, strength much like anavar.
or... If you really want to give your balls a squeeze and do something (would not do myself), Halo is an extremely androgenic compound that will add a ton of strength as well as aggression with little weight gain. Downside is it shitkicks your liver so 4-6 weeks would be max for this one.
Someone correct me if im wrong here, but yeah bro, AT LEAST stay natural until 2007!