I just harvested this weekend...I gave em 24 hours of darkness right before chop and harvested at midnight...I have no idea why I do the darkness thing but I read about it somewhere and it became tradition...
As far as the midnight thing,I didn't wanna harvest on Friday the 13th so I waited till 12:01AM Saturday to harvest...Sounds silly I know,but we all have our little quirks and should do what makes us feel comortable...
I've heard some people talk about jump starting their flowering stage by giving 24 or even more hours of darkness before flowering...I've never done this so I can't give any hands on experience to this but I'd be hesitant to try this method on my grows...If I put 7 weeks into veggin' a plant,I can wait the 9 to 14 days for flowering to be established under a regular 12/12 schedule...I grow fem beans and do whatever I can to avoid the dreaded "H" word...