amount of light for auto seedlings?

how do you know how much light to give early autos without overdoing it or simply wasting electricity?
I have a couple of 30w 6700k CFLs.

I could use a 150W HPS but 98% of the light would be directed to the soil so it doesn't seem worthwhile.


With photoperiod plants I woudn't be bothered, but with autos you have a certain time window to get it right in veg.

You can use the 6700 CFLs for as long as you can get away with it. The most recent auto that I'm growing, I used one for the first two weeks and then added another for an additional week before turning on the LED.