If they were laying eggs, you would have evidence of that - EGGS. They begin laying around 5-7 months of age, as Angie K said. They STOP laying around 3 YEARS old. Yours are just having fun digging, which is completely natural for chickens.

Average is 6 months when chickens start laying eggs, not 2-3 years! Some can start late and some can start early as 4 or 5 months but that is when you feed them too much protien or layer feed when they are not old enough, How old are they?

they need to be about 2 to 3 years to be fully matured. they start laying eggs at that age.