i grew some seedlings under 12/12 from sprouting,think they're in one of my grow logs somewhere,should have some pics too,after about 2 weeks they started showing sex and finished in about 10 weeks from seed,downside was it affected the yeild considerably,i got about 1 ounce per plant compared to 4 ounce per plant for vegging them for just 4 weeks,
so when you take into consideration it's gonna take 2 weeks to show sex,time that could be spent vegging,for saving 2 maybe 3 weeks in total growing time,i sacrificed 3/4 of my yeild,
upside is that i could grow them in much smaller pots so could grow more plants in the space i have had i chosen to continue to use this method,also it would be possible to make like steps in the grow room and introduce new plants every 2 weeks or so like a sea of green,after 10 weeks you'd be harvesting every 2 weeks
good luck with your experiment,keep it updated if you can,i'd like to hear your conclusions
stef