Sometimes when chickens get moved to a new location it frightens them and it may take a few weeks before they start laying again.The guy said they are 15 months old. They came from a laying house would be my guess.
I have had them for about 8 days now. The guy I got them from said they were around 15 months old. He bought a truckload of them so I am guessing they came from a commercial laying house? He said they were laying before hand.
It is also possible this person lied about their age and the reason they got rid of the chickens to begin with was because they were already too old and quick laying.
I'm not saying this is what happened but just keep this in mind.