I'm personally not keen on episodic releases, I tend to wait until its all out to play the full experience in those cases. My thought is take all the time you need to polish it to a point where you're happy with it, and release it no earlier. Though, if you want feedback as to whether or not the finished game will hit that right spot with us players... maybe do a "Prologue" release I've seen some games do, not so much a demo, but like the first chapter, first 30mins, however long you'd want that to be. Then you can use that feedback and reception to inform development for the rest of the game, however long that may take :)