Board Thread:Questions and Answers/@comment-25732247-20151114115517/@comment-24018437-20151114174537

There actually was a timeline on the official site, which said the three shorts take place after the first movie, but before the series.

As for ages, Gustav is currently 16. I think his age was mentioned in one of the episodes in 'Race To The Edge'. He said he had been working for the teens for three years now and that he was now Hiccup's age or something along that line. Its been a while since I saw that episode. Heather is the same age as Astrid (I think).

Not entirely sure about Gothi and Dagur. I think Dagur is two to four years older then Hiccup, and Gothi...At least sixty, that's obvious. But her exact age, I have no idea.