User blog comment:Martialmaniac/HxH timeline/@comment-4932025-20161212221030/@comment-5780397-20161213092357

Gon turned 13 during that arc.

It's Togashi that wrote the dates, though. The timeline was put together by a fan, sure, but we can easily reconstruct it from the references Togashi himself wrote, and we can verify them in the canon material. Ignoring them is going against pretty much every single instance in which he has written a date.

We also know for a fact he has grown: he was 11, and then he turned 12. I think the very least we can do is list both cases. I'll use Killua's and Gon's pages as examples.