Why this under help needed you seem to know the crack,im sure that you might even get away with a hour either way when it comes to flowering but its a test you will have to try,i my self will only ever flower on 12/12 off and veg under 18/6 i see no point in 24 hour light during flowering from test i have done there is nothing to be gained from 24 hr of light.
But i have done test over the last few week on root growth, i now have done away with the auto pot growing and growing in dwc,the roots are growing at least 3 ince dureing the lights of but then again i have not vegged in dwc i veg in coco and clay balls with a 50/50 mix of coco and clay balls with 50 % bio bizz the one with out added feed.I like to know what is going into the medium so a blank sheet so to speak.These are on canna a/b and rhizatonic every so often.
The mothers i have 3 of em 1 blues 1 jack herer and 1 cheese,also a cross of the blues and cheese so 4 mums in total just had a custom built unit for them,just space for one more mother, the plant i working on at the minute blues x cheese, crossed with the jack herer i have had longer than i care to remember.
Best to to stick to a time frame and stick to it,its too risky messing around with time during flowering just leave em on 12/12 off......
I would not ease them into 12 on 12 off just get them straight on 12/12 they will be fine.To be honest i think that plants sometimes produce better yeilds with a little stress.lets face it nothing we are doing is really same has nature,in nature the weather is never the same temp there are heavy winds.But the whole idea is to make the plants think its the perfect autum or summer in veg.Once you have your room keyed in then you will reap the rewards.
...................................................................tyke.......................................................................................................................................