There's no estimate on this at the moment. Even I'm getting zero information on what's happening. This process is extremely involved, but I feel it could be more transparent than it is.
There was a build log in the mod forum for a while that I could see (these usually reflect the ongoing build process pretty well as K works through things), but other than an odd post here and there, very little has been posted to it over the past few months. I know K is around because he turns up on here from time to time, but I'm not sure where he stands on the work at the moment.
I'm assuming he's still stuck on the script issue (last I heard there were issues with the migration script Plesk provided being effectively useless). The migration script sounded promising on the surface, but once we realized the script did not work as advertised and would not be an easy fix, "abandon the migration idea, get the server and custom integrations working, and invite everyone again" would've likely been my course of action if it were my decision.