Getting pregnant

Okay so i ve read a post on a webforum about a girl that said she had sex with her bf before her period n he came in her n she got period after that, she also said it was usual period so no light bleeding n stuff like that .. n then i also remember all these women saying “u can get pregnant at any time n even with precum” but then i think - this guy came in her so.. idk so confusing .. so what do u think about that?