If i messed around a bit on 6th day of cycle, and i start birth control for 1st time ever on 8th day of cycle will i ovulate? get pregnant?

Birth control pills: are not necessarily effective the first month that you take them. You should use an alternative form of birth control (eg. double barrier) in addition to the pills until you have completed one full pack. If you have had unprotected intercourse, then you could be pregnant. Consistent condom use is the best protection from sexually transmitted diseases (STD).

Can check preg. test: In the past, women started BC pills after having a period (the period usually confirms she is not pregnant before starting pills). With teens and some women, they might have sex and get pregnant while holding on to the pills, waiting for that period to come. So, it is ok to start pills right away, but also use condoms the first month, and check a urine preg. three weeks after last unprotected sex.