I run a 24/0 cycle for vegetative phase, then a 13/11 cycle for the flowering cycle, and then 3 days of darkness just before chopping down. (Note: 13/11 = hours on/hours off). The length of these cycles varies, I let the plant tell me when it is ready for the change. But average is 5 to 6 weeks of veg, and then 10 to 11 weeks of flower, Also I go by the color of the trichs to determine when to harvest not time.

JG