Looking good actually.did the cotyledons just fall off recently? Looks to be about 10-12 days old? Maybe a bit older since you use 18/6 . I agree with taGyo, and personally i still grow with cfl's and hid's. So im gonna say 24/0 would speed you up a bit. Dont worry about changing light cycles in veg just dont go below 15hrs untill you want to flower ect.