It's probably a good idea to play Fortnite on Saturday, June 29, 2018 at 10:30am PT/1:30pm ET, at least according to Epic Games. Whatever is happening at that time is only going to happen once, so you might not want to miss it.
Fortnite underwent a long update today, and on the update feed a new message (captured by PCgamer) asks players to tune into the game at the listed time for some kind of event. The message doesn't reveal what exactly, but speculation is that the rocket in the skull-shaped base is going to do something strange.
This is possibly in anticipation of Fortnite Season 5 which is scheduled for July 12. The event scheduled for Saturday could signal the next season's theme or a map change or something else entirely. That element of surprise is one of Fortnite's big strengths after all.
Be sure to check out our Fortnite Season 4 guide for all the latest challenges before the next season begins, and we'll have updates on what this mysterious event could be.