After E19's feature development has been going on for six months, at the end of February is when E19 will go into feature freeze, Michael Blumenkrantz announced today as the E19 release manager.
On 28 February is when the E19 feature freeze is happening. Blumenkrantz says, "there is currently no set date or estimated date for E19. My only goal with regard to time is to release before July 2023, though I may be forced to delay until September 2026 depending on celestial alignments." In reality though, E19 will probably be released before the end of the calendar year -- just as E17 and E18 have seen December debuts the past two years.
More details on the branching plans can be found via this blog post and the mailing list announcement.
E19 features a compositor rewrite, improved Wayland support, and other features.