How many chapters/parts do you thing there will be to this story? Also, how much content comes with each update?
I always shoot for at least two hours of content each update, but the next one will likely be shorter as I focus on fixing up some older events and polishing the game.
And I'm thinking the project will end up somewhere around 9~12 chapters long depending on how accurate my estimates are and what story beats may get changed along the way.