How much headroom do you actually have? I like topping plants maybe you should look into it, as well as some lst you can really control plant canopy's. I have 3 girls in flower for 5 1/2 weeks now that are no taller than 20'' from soil. I topped at 5th node and tied every branch down to the sides of the pots spreading them out.
If you don't plan on any training I would suggest you flower soon. They are going to stretch like hell the first 2 weeks of 12/12 especially using cfl.