Dude,
I just started my first cycle ever about 2 weeks ago. The first shot was the hardest for me. It didn't hurt at all, just a little pinch but I was scared of the unknown as far as my mind was concerned.
I have had 3 shots total to date since the start of my cycle. I am doing 400mg of deca and 400mg of test in one shot. I start to feel the soreness about an hour or so after the shot. It ususally goes away in like 3 or 4 days. It is nothing real bad, but I can feel it. Also, I alternate left and right glute from week to week. Just so you are aware, you may and probably will feel some soreness.