Way to young. Honestly GH will pretty much do nothing for you at your age. Second, Gh is spoken of as some great thing that will transform a person. Well it won't. Gh on its own in men around 30's can help with improved sleep, endurance, skin appearance, overall health and well being by replacing doses lost, and as noted can assist in leaning up.
Gh as a mass or muscle builder on its own is about as good as all the shit they sell at gnc, it simply doesn't happen. Now when you add AAS into the equation, Gh will have some synergy with any anabolic/androgenic hormone. To add mass, you either need 3-15 of real pharm grade USA serostims which would cost as much or more than most guys pay in rent or mortgage each month.
It is a long term commitment, the 6 month idea is a number that's been thrown around the boards for years, but isn't any exact science. But again, don't expect much but a hole in your pocket with Gh. Yes it will help remain or get lean, and there are many contradicting medical journals as to its efficacy in creating new muscle cells and if IGF has any role in that at all.
But guys who run good Gh, which 99% is fake, know that it can be helpful. But to add mass, with AAS, you still need large doses of the generics and foreign Gh. So many guys have went on and on about how great Gh is only to find out what they were using was fake all along.
At your age, you don't need anything but hard work. Your body is producing all of what us older guys are striving for. Don't get me wrong, Gh has its place, but its with experience, AAS, insulin, etc.
If I were you, I would focus on diet and training, you can do a lot with that. Some creatine can help with strength but give a puffy look, protein, bcaa's and eaa's should be added.
When you get older then look into some of these things.
If you are dead set at trying something out, try Ostarine and GW501516. Ostarine attaches to the andro receptors and will give good strength, and the GW will provide you with crazy endurance. Any further than that and you are damaging your body or wasting your money.