Just started playing the game after waiting for a few years

[Taika]

Sounds interesting, But what is the Yo-Kai watch events?

It's a seasonal event going on right now: http://na.finalfantasyxiv.com/lodestone/special/2016/youkai-watch

There's also a megathread for it on these forums: http://forum.square-enix.com/ffxiv/t...gathread-Guide

You can start it after reaching level 15 if you wish, but there are many other ways to gain exp and you're in fact likely to outlevel our main scenario just following the most straightworward path.