Talk:How to Train Your Dragon: The Hidden World/@comment-35966002-20180625135721/@comment-31135394-20180702071608

That was a guess by Kevan Shorey; one of HTTYD3's animators; on Twitter. Someone asked how old bearded Hiccup is, and Kevan answered "maybe 30", so it would be about 10(ish) years after the main narrative of the film.