User blog comment:Martialmaniac/Urgent adition and correction to Gon's page - Aiko and Paper/@comment-4932025-20170205005755/@comment-5780397-20170206191751

In certain points we're talking about two slightly different things. The date of borth of Gon and Killua should be exact, since at the time when the panel with the date was shown, there were no issues with the continuity yet. Regardless, I'm open to discussion.

Just to be accurate: that the Hunter Exam is a yearly event that takes place in early January is in the manga; the number of Hunter Exams that passed since Gon's is also in the manga; same for the date of the Chairman Election and that of the departure of the Black Whale. What is interesting about the latter two events is that they both took place on August 8th, so they could not have happened in the same year. This is supported by the presence of a Hunter Exam in-between and Mizaiston speaking to Beyond thirty-five (his own words) days before August 8th.

While I do insist that the timeline age should at least be mentioned in the Trivia, this is also the reason why we can't say that Gon's "current" age is 12, as one year passed since the last mention of his age. All we can say is that 12 was his age during the Chairman Election arc.