birth control and period question

so I just finished my first three weeks of birth control, I take my first sugar pill today, which means my period should come sometime next week. i still don’t completely understand how birth control will affect my period. should I expect it to come monday or sometime in the middle of the week? i feel like I am experiencing PMS symptoms as i am pretty emotional. can I still experience PMS symptoms even when i’m on birth control?! lol, I seriously just don’t get it. i’m under a lot of stress as final exams are next week and i’m leaving my bf for the summer and we are going to be 4 hours away for four months, so i’m also worried my period will be late because of the stress. idk. just need some advice on how this works and what to expect period wise.