It's mostly a waiting game, however, a rule of guidance says hens usually start laying around 20 weeks or 6 months of age. Some start quite a while earlier and some start a lot later. Another indicator is the redness of the comb & wattles. The redder the better. Another sign is when the pullet starts squatting, like if you were going to pet it on the back and it lowers itself into a squatting position (like it's getting ready for a rooster to mount it). Those are all signs that a pullet is close to age laying, but as with people, hens are all different. Yours will start laying when it is the right time for them.
