Kander said on discord yesterday that... Kander at 9:50 PM New hunter content is slated to go in with mid-content.
keep an eye on discord - Nothing has been officially announced that I've seen but i'd guess within 2 to 3 weeks.
It should be tomorrow if my calendar isn't off. But that is an assumption based upon a 12 week expansion. If this one is extended 4 weeks like the last, then I guess mid expansion could be 2 weeks out.