Practically a whole month, at first the update was supposed to arrive at the beginning of this month, but it was delayed until the 20th because he still had to finish a scene, then Inatari said he'd better leave the release for the 30th because some details were missing in the Marin scenes, and now it was delayed until at least April 3rd for the same reason.
Practically the delay is due to the same thing, it seems that Inatari was not convinced with the scene animations because of small details and decided to delay the update until he was satisfied with the animations.
To avoid that kind of problems, he is looking for a writer to help him to take some work off his hands, but in my opinion maybe he should look for someone to help him with the animations which is where I think he is having difficulties lately (I think to animate using Live2D cubism, I'm not sure).