There will be continuous updates, as I'm trying to complete at least one route at a time.
Here's a progress of how it works:
(Aiden is at step "Write important scenes and plan out CGs" whereas Neil is at "Complete Script")
So you'll never have to wait until the 'full game' until you can play a route. I'll always try to release an update that includes more chapters. Some people like to wait and play it until it's fully finished, but personally, I hate waiting for months/years (and in the meantime totally forget about it), so I like releasing small updates each time.
Route order at the moment is Neil > Dimitri, and probably next up is either Aiden or Caine, though most likely Aiden. I'll probably have him added if I write his introduction chapter (I don't write chronologically).