IUD Insertion Next Week. TERRIFIED

Hey guys I'm getting the Mirena IUD put in next week (Wednesday) and I'm terrified. I've heard it's extremely painful. Can anyone describe the pain? I'm scared!! Also do you get your period upon insertion? I'm going to be traveling Saturday and am wondering if that means I'll be on my "period" at that time. I'm not due for my period until two weeks from now.