Is it the concensus that 12/12fs results in a loss of potency as compared to a 3 - 4 wk veg? Also does anyone have 12 /12fs experience with these strains: kush(og # 18, lsd, (dp) white widow?
Sorry I don't have experience with those particular strains.
My experience with 12/12 from seed has been good, I doubt there is a NOTICEABLE drop in potency. I'd argue that it's more natural for a plant to grow 12/12 from seed then it is to veg it in 18/6 and drastically switch the schedule to force flower. 12/12 from seed is a fine way to see what you are working with, if you want to keep the plant reveg it, it's not that hard every plant I have tried has reveg just fine. Then again some say reveging does harm too... keep in mind all these people say this stuff based on opinion rather then fact.
Sadly I don't have testing available to me or I'd already have this resolved
tip, top/fim when you see preflowers show up 4-6 node ish 3-5 weekish
It won't slow down and you'll get some nice flower stretch and more tops. Heavy yeilders can be dangerous 12/12 from seed molds can take over huge nugs quick.