Hi
I by far am not an expert but in my opinion I would do 12/12 from start. Why I say this... I am currently doing my first grow and journal and started in a larger space then a pc case (18" deep, 40" wide, 23" height)and with cfl's. I started my 4 plants on 18/6 and when they were 32 days old put them on 12/12. My plants are into 9 days of flower today and one is over 28" (not counting pot it's in) and growing every day. On day 6 of 12/12 started one of my plants showed female and one male. I am currently waiting on the other two to show. My 4 plants out grew first grow space, I had to make larger grow space they out grew that now they are currently in a closet grow space. My next grow I am going to do the 12/12 from start.