flowering needs at least 12 hours, you can do more. 12/12 is usually a easy way to balance the dark hours and light hours. If size is an issue why don't you just LST or SCROG? Topping or FIMing help a little too. I would lst/scrog wait at least 2 more weeks and then go 12/12. My plant would probably be 2 1/2 feet if I didn't do any traing, but i've kept in just under a foot and let the lower nodes/branches get some light.flower at 12/12. 18/6 is what many of us veg at. some do 24/0. but flower has to be 12/12. you have a long ways to go yet. in flower, the thing must be in TOTAL DARKNESS for the off 12! or it will not work out.