That thing is still just a baby, give it time. It does appear to be stretching a bit though, you may want to get it closer to the light(s).Depending on how big a plant/yield you want, you can force flower at almost any time and this will speed up the sexing of the plant. I personally wouldn't go 12/12 on that one till it grew about another 8-10 inches, but it's your baby, your choice as far as height/yield. Patience is a HUGE part of growing.