I do belive that will hurt your yeild depending when the 12 hr cycle comes..
Try super cropping, then tie them down. It will make your plant bushier, but you wont lose out on the colas as much. (Dont forget to use tape on any that happen to snap open)
If you do decide to top, though not ideal, try to get the curtings to root so you can still get those colas you cut off! (Usually you want to root bottom branches due to hormone levels)