https://www.techradar.com/news/its-official-new-iphone-2018-launch-event-is-scheduled-for-september-12

Apple's New iPhone 2018 launch event is Wednesday, September 12 - the invites have gone out to the press.

That's the date we expect Apple to announce the iPhone 9 and iPhone 11. There's been little mystery to the timing and design, though the names remain unknown.