Here's some info on when chickens start laying eggs
Chickens usually start laying between 16 to 20 weeks or around 4 to 5 months old; however, it can take a little longer for hens to settle in and start laying especially if they have been moved to a new area or spent a fair amount of time in transit.
This is not always the case though with some breeds or individual chickens laying sooner and I've even seen them lay whilst being transported in the back of a vehicle!
Laying chickens can "go off the lay" due to natural causes like the onset of winter or just time to give her body a rest and this can last several weeks. Also, chickens can go off the lay because of unnatural causes such as: a fright (from a predator attack); stress from being moved; sickness; parasites; not enough feed or water; and overcrowding.
When you first get chickens or even get a new hen it's always fun (particularly for kids) to guess and check to see when/if the chicken has started laying. It might not happen right away but it will happen…
