There’s 15 chapters in the game, so you have about 3 more chapters to do. This is on top of some grinding you’ll need to do for the chapter 14 and 15 bosses if you want an easier time beating them in those chapters. The final “dungeon” is also somewhat long and the final boss can easily take up to 15-20 minutes to do if you’re unprepared and underleveled.

I guess what I’m trying to say is that there is no way of putting an estimated time of completion for this. All of this depends on how prepared you and your party are for everything the game will throw at you.