Complete bro science. As soon as you inject a steroid into your body, it is released into the blood stream and transported throughout the body to perform it's mechanisms of action.
It makes no difference where you inject. I personally like to inject in large muscle groups like glutes because they generally cause the least PIP.
This is not how steroids work. When you inject it is going deep into the muscle (whatever muscle you inject into). The hormone is then absorbed into the blood stream. It makes no difference where you inject. I would pick the easier spots though like glutes and delts especially for a first cycle. You will get less PIP this way.