I always started wet sanding when I got to 400 grit during the final polishing process. However, I began following a dry 320 with a wet 320. I think I might have saved myself a significant amount of over all time by doing this. I might try this down to 240. What do you guys do? Maybe better suggestions? And I never "polish" I just go to 1500 wet sanding (400 - 600 - 1000 - 1500).
Oh, and I started using less water in my wets. I think that has been helping quit a bit, too.