Everything makes sense. Demon hunter starting zone in the vaults takes place at the same time as Broken Shore so they have to be released together. They all meet up afterwards. In PTR you were sent to do demon invasions right after so that's not surprising either.
Pretty sure what they meant was give a couple of weeks to let players get used to class changes and transmog. After that it's w/e. Dark whispers might also still be the week before.