Each pullet will lay at their own time. All of my chickens had the same hatch date, 3 EE, 2 speckled sussex, 1 silver laced wyandotte, and 1 exchequer leghorn. The first to start laying was one of my EE, and the last to start laying was another one of my EE. I got my first egg 1/4/2011, the last to start laying didn't lay her first until 2/17. Same breed, same hatch date, but a month and a half between start of lay. Some breeds can take 8-10 months, and occasionally longer to start laying.