how long until chapter 3
No clue, but the dev posted dev log #16 on patreon 4 days ago... I unfortunately can't read it since I'm not subscribed.
BUT I have an estimation based off of the game's initial release and Chapter 2's release. So the game was released in July while Chapter 2 came out in January. That's about 6 months or half a year later.
Based off of that and assuming Chapter 3 is taking roughly the same amount of time, Chapter 3 MIGHT drop in July as July is 6 months after January. However, I can't read the devlogs so there might be something like "took a break" or "had trouble working on this..." , etc, etc in them. So it might come out in August or September instead.