Period normal cycle

My period cycle has been consistent ever since I got the IUD back in February. It's been at the end of the month usually around the 20th, this month however I got it on the 15th and today ( 30th) I feel like I'm going to get it again; is that normal? I'm also nervous because on October 4th I'm going to go see my boyfriend and I don't want to be on my period when I go see him because I want to have sex with him but if I get my period soon that means my cycle has changed toward the beginning of the month.