Clones need legs.. or roots before flowering.. but you might get away with vegging them for a week or two when the others are flowering and then putting the clones in with the seedlings. Clones assume the age of the mother plant.. thats a big concept and the reason why they have different nutrent reqs than seedlings. They will look and act different.

CO2 is the cats ass in all I have seen.. mostly with veggies though.. as I have the same plants outside in the TX sun and then inside under floros and "enhanced" CO2.. the inside plants are bigger than the outside ones!

The "enhanced" part is me and my roomate breathing all the time.. inside CO2 is steady at 1800ppm (by digital CO2 analyzer read daily) and probably will stay up as long as this heat keeps us from opening windows and stuff. Cant beat free! Except that I bought all the equipment just to find out CO2 levels were already nearly at toxic levels to the plants without any addition.

I have never really done the soil thing.. not for anything that serious.. I mean ive dropped seeds in soil but I learned all I know thru hydro.. A VERY worthy investment for those who like to tinker with the forbidden arts.. but no small investment either.. you will spend over a thousand of dollars to make a good hydro garden.. when you would only spend a couple hundred to do the same in dirt.

If those clones have a good set of roots by the weekend you may concider flowering.. I like to experiment so I might take one clone and flower it along with the others and hold the others back for a bit.. you get to see what happens and not risk everything.