Is there any prblm if use ipill. Or not?

Hi doctor I had sex with my girlfriend 1st of this month but very very minute sperm had came I think even not one drop also into her inside ,her period date is 2nd of this month if she got period correctly by 2 nd of this month then can I expect no prblm with pregnancy or else did she has to use ipill She is waiting for the date? Actually it's been completed only 11 hrs after sex so, can I wait until she get period or am I have to give I pill ? And she is saying if got period correctly then no prblm if not came correctly then has to use ipill What she told Is correct or not? My doubt is even one drop also not went to inside So y need to use ipill , if she use ipill she will get date prblms even if she got date correctly am I have to give ipil within 72 hrs ?I need to give ipill or not? Pls share ur suggestions