Looking at your pics gives me the itch again. I used MH/HPS switchable light and would start flowering them at about 6" tall. They would already have 2-4 nodes on the m though. I've never tried CFL's. If you do get into height problems, you can always tie branches down to where they are horizontal. This is best done early while the stems are still rubbery and bendable. Also, have you read about supercropping? Interesting stuff. For a first timer, you seem to know what you're doing. Keep it up.