Hi!
I was wondering if you could tell me more about that Toothcup event please?
Sure! The event itself is being managed by @toothcup-week, so they're gonna be the best resource/authority as to what's actually going to happen. They're currently accepting prompt suggestions for the next couple of days, and then in about a week and a half they're planning to show the list. This means anyone who wants to participate has about a month and a half to prepare stuff to flood the fandom tag with share with other fans.
I'm particularly drawn to it not only because, well, Toothcup, but also because it's open to all sorts of Hiccup-Toothless relationships (platonic, romantic, familial, friendly... possibly sexual but I haven't asked), whereas a lot of other ship events tend to focus on one aspect.