The main factor to keep in mind is that a plant can double in size during the first 4 to 5 weeks of flowering. Some growers will have space restrictions.
You can run 12/12 from seed drop but the plant won’t go into preflower/flower until it’s sexually mature, typically it takes 4-6 weeks to become sexually mature. I veg my plants for approximately 6 weeks and flip the light. Yield is dependent on the strain and training techniques
Happy cake day @AndThis. Agree every plant is different. I usually veg for 6 weeks after they sprout since I do 4 plants in a 4 x 4 tent. Get 25 to 35 ounces when I do that.
In my opinion, photoperiod plants should not be put into flower until they are at least 3 months old (when grown from seed). This gives the plant time to reach sexual maturity, develop good strong branches, and you get better results than you would from a younger plant.
If the plant is grown from a cutting, then you can flip it sooner because it’s probably already sexually mature. However, the plant needs to have a decent root system and be structurally sound (decent stem and branches) otherwise it won’t produce many flowers. Most cuttings take 2 months before they have developed a good root system and decent stem and branches. And 3+ months if you want to train it for a screen of green.
With plants, don’t force them into flower too early. Let them grow and develop good branches and a sturdy stem, then flip them. Then you get a decent crop.
IMO plant veg to flower considerations should always include how big the grow space is.
As a small tent grower 31x31 2 plants will rapidly fill a tent. I flipped at 6 weeks and still struggled flattening out the canopy. Hopefully training will go better next time as I see my disorganized approach worked but is not optimal. I also saved as many fans as possible for energy later in the grow.
Winner winner, over crowding a tent to get more plants affect the yield….lower fruit is never as ripe as the upper, small larf nugs down low on the plant, risk of mold and plant maintenance is difficult
Photo on 12/12 will act just like an auto. About same size and yield. They will self flip at maturity. This is a quick turnaround photo. I do it here and there when have a.lot of beans. I prefer to veg out my photo though. They are our main medical and seek yield.