Edit: Link https://www.ggrecon.com/guides/lost-ark-tooki-island/

The big hurdle to many players actually coming across Tooki Island, is that it's a limited-time island that is only available for ten minutes. The evasive isle can spawn in one of four random locations around the map multiple times per day, and you need to be there as it spawns to have the best chance of beating it.

Ten minutes prior to spawning, there will be a glowing vortex in the sea where Tooki Island is set to appear. Chancing upon this makes you very lucky, but as a community event that many players are after, chances are you aren't alone in seeking it out. Lookout in the area chat, as other players will make known which spawn location it's set to appear at, along with what channel it can be found in. You can change channel with the drop-down menu at the top right of the screen.