They used CG throughout the show, but only started using it heavily for space VFX in season 6. They used plenty of stock footage in the last two seasons, so it's not like they went full CG at some point.
You telling me the huge space battles in The Way of the Warrior
and in Call to Arms
were done with all models instead of CGI?
I think Call to Arms may have been mostly CGI (and is after all, only one episode before season 6 so I'd say it gets covered by the original quote) but Way of the Warrior was indeed mostly model work. There's a lot of Trek Christmas tree decorations in there filling in for the background ships.