As soon as possible.... more light now will help keep the notes tight and keep the stretch to a minimum... look into HO T5... with cfl side lights... just a suggestion.... http://www.amazon.com/Light-4lamps-DL824-Fluorescent-Hydroponic/dp/B009GU4RMC.. not a bad price for one plant... plus you can change from the 6400k to 2700k for flower and or mix and match to get a good mix of spectrum... more bang for the buck