C02 with new starts!?! Should I hold off, or go for it?

Just planted my clones. Room temp 80 lights on, 70 lights off. Have a swamp chiller to control environment.

Is it too early to add C02 to my room. I have a great set-up (c02 burner with "the brain monitor" to control the ppm level's.

Should I then get these little clones on the program or wait.
If so, what should the ppm's be at (I know that 1500 is great once they have established themselves, but should I go with that as they have only been planted 4 days ago from their cloning trays).

Also, I am running 1000 metal halide lights, and at the moment they are about 2.5 - 3 feet above the plant canopy.

Once again, I know that 18 inches from tops is ideal, but I don't want to burn them from the start.

Thanks for any advice gang.

no wait about a week the set the ppm to about 600 and gradualy increase until you reach 1500ppm. 2.5 - 3 feet is good this early, when better established you can lower them. all the best. jimmy