Really dude, dont do it. You will probably stun your growth and since you probably are not fully grown you will miss out on a wider frame which usually comes around ur early 20's. When I started weightlifting I was thin and after a lot of basic reading I thought I knew everything. The fact was that I was doing too heavy weights, ate to little and the wrong stuff and had no clue of how my body responded.
After taking it more seriously for some 2-3 years I know my body better, much better nutrient knowledge and Im actually improving strength and bodycomposition at a rate which is acceptable. Im 22 now and wouldnt even consider even doin a cycle until I'm 24-25..if ever. I still have a lot of trial and error to do. Ive found out a few things along the way to where Im at now. Im really glad I didnt start juicin when I at your age. Please, for your own good, wait at least til ur 21. Gains will come´you just have to seek new information and try out new things. Patiens..... been stuck for a month aint long enuff to even consider juicing.
Good luck
/Xizor