I can stretch my view and say that 1997 is a transition year, but 1998 is definitely psy-trance. In my opinion TIP Records Phosphorescent compilation (1996) marked the beginning (or mainstrem use) of psy-trance and the following death of goa trance.
Check the compilations from 1997:
Psynews compilation reviews 1997
The major labels all released psy-trance 1997: 3D, Airborn, Black Rhino, Funk, Let It Rip, Made On Earth, TIP Singles 1-2.