Im going to be the first to say this but probably not the last. At 20y/o you are to young to be messing with slin or AAS.
8iu as your first dose is just stupid. You may be under the impression that since you weight more you can handle more slin. Thats not the way slin works. No matter how big you are small amounts will effect you. Start low and pyramid up.
Site injection will not help because you should be giving the slin Sub Q(into the fatty layer) not into the muscle.
Im not trying to flame you bro, but one mistake with this stuff can and will kill you.