A number of factors can influence when a duck may commence laying. Day light hours, season and breed are the most influential. Muscovies and ornamental breeds can tend to be more seasonal layers- and may not lay until the spring following their hatching - meaning they can be nearly a year old before they lay. Whereas something like a Runner or Campbell who lay year round are more likely to start when 22 weeks give or take a few weeks regardless of the season.
Generally a duck is physically mature enough to lay eggs as early as 16 weeks but an average is more around the 22- 24 weeks of age mark.
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