Hello!
As Gyste said, we won't be able to give an answer before the game is finished. In particular, because the final version will contain gameplay features, conventional visual novel reading time estimates will be inaccurate.
That said, we made an estimate on Tumblr a while ago. You can read it here: https://anomalis.tumblr.com/post/164375925632/hi-there-not-sure-if-this-has-been...