I rather think that people do not believe that a pullet started to lay at three months; if someone told me they had that happen I would have a hard time believing such a thing, but it did. The hen hatched May 1st and during the first week of August the pullet was laying and by the end of August she was brooding-none of the eggs hatched, but they were fertile.Chickens can molt before they are a year old.
Your 6 month old could lay at any time. Of those 11 serama chicks I hard hatch last spring, seven were pullets. One started to lay a few days past 3 months, a mink killed one, four started to lay around 4 months of age, and the last pullet started to lay a week past 5 months.