The steam page that they put up, recently, for Echoes has December 2017 on it.
The thing that bothers me the most though is the ever shrinking content promised for echoes. The kickstarter said 15 to 25 hours. This page, I think, at one time said 15 plus hours and now it's down to 10 plus hours. This page says 24 plus endings and yet the steam page says "two distinct canon endings per character". Maybe there will be numerous short, bad or early, ends as well to get to 24 endings. Also, based on the steam page, there will only be 10 CG's, which will be done by the new artists. This probably means that the mini route/s won't have CGs.