Technically you can switch to 12/12 whenever you want. It all depends on how tall you want your finished plants. Needless to say your yield will increase with the size of your plant usually as long as you can provide enough light and everything else it needs.

Upgrading your lights will be a huge difference.
GetThisOrDie Reviewed by GetThisOrDie on . First timer questions Hello Cannabis community! How long does it usually take for a plant to enter the flowering stage? I have heard once you put it onto 12/12 it will change stages, but how do i know when to put the lights on 12/12? And What is Auto flowering? Do you not change the light hours, and the plant will flower when ready? And finally, how much of a difference do you think i would see, if I upgraded my lights. Now i have 1 120 watt, and a 3 26watt CFL's. Thanks for your time, and input! Rating: 5