...the big thing you'll want to focus on here is not to stress the plant when you do change your photoperiod. If your on 24/0 now, switch to 18/6 for a short period before you switch to 12/12. Too quick of a switch to 12/12 from 24/0 is said to induce hermies due to the unnatural photo change so quickly. FYI, you'll get many opinions on this....everyone has something different they like to do. Just think " LITTLE STRESS AS POSSIBLE" to be safe, whatever you try.