All good advice here, I would suggest watching them closely as well. My pullets have surprised me any number of times by laying early at 16 weeks and picking a totally unsuitable spot to lay and Every darned one them will decide that "THAT" spot is exactly where they must lay. I once found 15 eggs under an old board against the side of the run. I honestly couldn't figure out how they even managed to wiggle under there to lay, not to mention they had to have all been contortionists to even lay without bonking their heads on the low "top" to their chosen spot.