It's still a bit too early to say, to be honest. I think the next update will be a bit small, since that's when the groundwork for combat and roguelike elements will be introduced and I'll want feedback on that stuff asap. "Optimistically" I feel like it may be three months, but realistically six months is a safer bet. But story wise, you'll be introduced to each imps' respective summoner as well as their own motivations!
And thanks! Character writing is probably my favorite part of these projects, so it means a lot when people like my little goobers