How long does it take to know whose the daddy?

so I have a breeding pen up and running for just over 2 weeks with my faverolles and just prior to getting them set up Biggins had an pop at one of the hens -you see they were very close. So I was wondering how long it would take to ensure that the cockerel now (Bigfoot) would be the father?? I thought it was 3 weeks and was wondering if anyone knew for sure? Saying that though cochinXfaverolles would be very cute!