How long do chickens have to be laying before the eggs become fertile. The rooster has been making his rounds and tending to all the ladies. I have 13 ladies to one mature roo and he is definitely doing his job. How long does it take before the girls start laying fertile eggs? Next question: If I have new layers that have just started laying how long before the eggs can be incubated? I have Brahma pullets that will start laying soon and I want to start incubating for the spring around January so I have enough hatched meaties by the time it's warm enough to put them outside.