Welcome to BYC! Please make yourself at home and we are here to help.
Drumstick Diva has given you good advice. You can never force a pullet to lay, they have to lay on their own time. But there are ways to encourage them. Here are some other great ways to help.
Install the Nest Boxes!-Have the nest boxes in place by the 16th week because pullets begin to “play house” and sit in the nests, arrange the bedding and practice soothing lullabies at this age.
Keep Up a Routine and Minimize Stress!-Hens like a routine. It helps them not get stressed as they will know what to expect in the day and when. All chickens develop a pecking order also. So, a way to not stress out chickens is suddenly introduce a whole bunch of new birds to the flock, as they will have to find their place in the pecking order and it will stress out everybody, including you! As you will notice, chickens will set up a routine amongst themselves. Feed, water, collect eggs, clean and do other chores on time and keep up on you and your birds’ routine everyday. Your flock will soon be happy, stress-free and healthy, knowing what to expect!
You will notice that your pullets get red faces, large combs and wattles and start squatting before they lay.