Birth control.

My doctor gave me birth control to help with my cramps. I get them really bad but I have a question. My period is supposed to start soon but I still have a week of pills that aren't the period week pills. Will my period continue as normal or be the week after when I take the period week pills. Or is it just all screwed up until my body gets used to it. I'm just curious if anyone knows. :) Also I've had a lot of acne since I started taking the pills is this normal?