I assume that you chose to end your OP the way that you did because you already know that people are generally going to advise against steroid use at 19. It also suggests that you aren't going to be particularly receptive to advice if it isn't what you want to hear.
First off, if you are in amazing shape for your age, with the possibility of turning pro in the near future, then you should post a picture of yourself. If it is the case that you are ahead of the field then people may offer different advice if you can make a career out of competing. If you simply want to take steroids to expedite gains thinking it will enhance your hardly even begun PT career then i think this is misguided and a bad reason to start using.
Second, the info you have given regarding the cycle is too vague and what you have put together doesn't look good to me. It looks as though you don't understand the basics and Deca, in my opinion, is a terrible choice for a first cycle. You need to lay out a proper plan.
For me, the main reason you shouldn't do a cycle at your age isn't the growth thing you mention, it is the fact that you are so early into your adult life you simply haven't lived long enough to be able to make a smart decision here.
I hope that you don't consider this to be a bullshit troll answer, but rather someone 10 years your senior trying to offer some perspective.