Lots of factors come into play. Local wrather, additional lighting, nutrition, number of birds in the flock, age of hens, health, parasites...plus the individual hen herself. Mine begin laying earlier when I add lights to the coop. They slack
I am thinking of selling them at day old. Just because it doesn't take me long to bond with them and not want to let them go.I know thats wierd!
I usually give mine about 2-3 days just to make sure they are eating & drinking & I encourage people to put them in with chicks to help teach them. I always hatch poults & chicks together & have them available to go with the poults.