Personally I would start off with that 600 as far away as possible until they get to about 8" then drop it a few inches daily till ur about 14 inch from canopy. You just starting one seed with that mighty bright light? I don't deal with seeds. But for cuttings I just use a single 250w cfl with a homemade double parabola reflector to light my 4x2 clone box. Babys don't need to be pounded with light, just to be convinced that is light 20 hours a day. Watch ur temps aswell stretching is caused by high temps and the last thing u want is massive internodal spacing. As for nutes. Wait till you see signs of vigorous root growth before using nutes. Allways feed with 1ml/L of 50% H2O2. Hope this helps