The most logical opportunity would be at the iPhone launch.
During the analyst conference call after the most recent quarterly earnings announcement Apple CFO Luca Maestri was very clear that this year’s iPhones would release a couple of weeks later than usual. There was zero expectation (at least by sane people) that iPhones would be part of today’s announcement.
I expect Apple will have their iPhone event in a few weeks. That would be the most sensible time for a new AirPods release.