They can stay fertile for 3 weeks, but fertility tends to drop. Most breeders wait 4 weeks when switching roos.
Ok, so they should still be fertile... Good. I still have to find a roo, or just wait for one of my chicks to get old enough to cover the hens.... How old are they generally when they start finding the girls interesting? My definite roo, has no interest in any of the other chickens, and runs squawking from any that get too close... we have named him Rogue!