It is not all that good for hens to start laying too early. It depends on the amount of daylight, if it is increasing or decreasing, and also the breed of the chickens. High-production breeds like a modern sex-link might begin to lay at 16 weeks with increasing day-length in the early summer. If you want to have them lay early, you have to control their light carefully. This time of the year, the day-length is already decreasing, so you might consider adding light in the morning to keep the days long like summer! You need to convince your hens that it is summer, with ~ 14-15 hours of daylight or they will not lay, or might start to lay for a couple of weeks, and then very disappointingly, stop laying in Sept!