I'M just wondering does anybody know about how old chickens start laying and are there any exceptions?
In my experience this is a 'how long is a piece of string' question. Every hen could be and probably is an exception.
I reckon they COULD start laying from when their combs are fully developed and they are fully feathered and all that stuff, but whether they WILL start laying then is enbtirely up to them. We bought some 'point of lay' Warrens last September which didn't start laying until late April this year when we started feeding them layer's pellets and keeping them in until they produced an egg! Mind you they are pretty productive now and we are selling quite a few at the farm gate.
I am sure some of the chicken experts will tell you different!
On the good side, we had an old Light Sussex bantam which still produced the odd egg when she was 7!
All the best DL