Broadly speaking DS9 used mostly models (apart from the wormhole itself) until around 1995 because 'Explorers' was the first episode of that series to use a fully CGI ship in the form of the Bajoran sailship (if I recall correctly).
VOY mixed things up from the start but they clearly started relying more and more on CGI from the third season onwards.
So, all in I would think that it was around 95/96 that the main switchover began to happen on the shows. As far as I know ENT was always just CGI.
'If the Apocalypse starts, beep me!' - Buffy Summers
'The sky's the limit.....' Jean-Luc Picard, 'All Good Things'
courtesy of Saquist