https://www.gamespot.com/articles/fortnite-downtime-announced-ahead-of-high-stakes-5/1100-6461577/

Following a slight delay, Epic Games is getting ready to deploy Fortnite's latest weekly update. Patch 5.40, which was originally slated to arrive earlier this week before the developer discovered a "critical controller issue" and postponed it, will now roll out for all platforms on Thursday, September 6, marking the start of the recently teased High Stakes event.

As usual, the update will be preceded by a round of maintenance, during which time Fortnite's servers will be taken offline. The maintenance period is scheduled to begin early in the day at 1 AM PT / 4 AM ET / 9 AM BST. Epic hasn't revealed how long the downtime is estimated to last, but previous maintenance periods have typically been brief, generally running for an hour or two.