Wisdom Teeth Tommorrow!?

I am gonna be awake and on gas and novacain. How bad is it really? I am really nervous. I am getting all four out. My top came in fine. My lower ones are impacted but not in the bone. He said he would section them. How bad is it??? I drank pineapple juice before the 12 hour countdown and I hope it decreases the swelling. What happens from the time I get into the chair and the time I get out??? I can't remember gas real well but will I feel it? What will I feel?