My main tip would apply to any light: watch the plants and give them what they ask for. When the leaves are flat and level, they're happy. When they're praying, they want more light. When they're twisting, taco-ing, or curling to reduce their surface area, they want less light.

I like to stay on the bluer end of the spectrum until the stretch is over. I keep the light on 24 hours in seedling, but people seem to get good results with some dark time, too.

I agree with everything ArtfulCodger said, blue spectrum helps tremendously in veg. I have been known to adjust light cycle in veg, really depends on if auto or photoperiod. Auto I would run 22--24, photoperiod 18-24. I've read that root growth is higher in the plants dark period. So when I have seedlings or clones I try to give it at least some darkness, ramping up in hours as it grows in veg. But I'm also the type that dials down photoperiod plants into bloom 1 hr each day gradually moving into 12/12 cycle. Full spectrum lighting helps plants, I still supplement my samsung 281+ & 301s with additional uvb, uva, violet & blue & far red fixtures at different stages of growth. Totally not needed, but I've collected them along the way. I figure best try to hit the right nm figures of light.