Many may know this tip but those who don't , it sounds interesting..
Interview with Adam from THSEEDS “Weed World” Issue 54
When Inducing flowering of plants to give your plants a good start, it is important to reset it's internal clock. To do this give the plant 36 (or 24-40hrs) hours of darkness before the first 12 hours light 12 hour dark cycle. Remember the dark cycle must be kept 100 % dark, any disruption can cause the plant to start to reveg (grow again) and / or hermaphrodite and we don't want any of that..By doing this the plant will go straight into flowering instead of adjusting from 18 to 12.
When plant is finished give it another 36hours and reset the clock again. This time the plant will know it’s finished and it will push out all remaining energy into its last trichome production.
Other good grow tips from Adam