I have taken clones from 12/12 and threw them straight into 18/6 with no problems. the fear is it might make the girls herm. I'm going to take three flowering clones and put them in diferent stages. 1 one im going to ease into the vegg cycle buy adding an hour2. is going straight to the veg box. 3 is on i its own box for 72 hrs of light and we will see how all fairs.