My Runners and Buffs who are also big layers started out laying straight 18 months before they took their first break. i was really getting worried then when they got close to 3 yrs they began to take longer breaks. And would go from Oct to Feb of the following year before starting back, now they are all but 2 going on 7 and they haven't even laid yet since last Oct. Only my one Fawn and White who will be 4 yrs the end of April has started back. My other one who will be 4 in June isn't even laying yet unless when I go to clean I find another duck egg. So I'd say by age 3 they will be getting past their long laying periods. Now I don't have your breed so this is really just a guess. But prolific layers probably don't have a long-laying life. They lay so much in their young lives. I stay away from breeds in my chickens that are prolific layers just to try and not have to deal with laying issues.
