I thought most chickens molt around 18 months, or after 1 year of laying, give or take. That is how mine always did. My chickens have always been April or May hatch except when I got 17 week old pullets in November (july hatch) one year. The April and May ones always molted in the fall and the July hatch started laying in November & molted the next year thru the winter. Just my experience.