24 hour dark period is well kinda pointless. if you want to try and replicate the days getting closer to winter then drop your light down to 11/13 then 10/14 theplant will know its getting "darker" out sooner but cutting all light is just going to make the plant do well nothing as it has no energy source to grow.
yes you can cut as much of the plant down as you wish and leave it in for more time to maybe get the smalled buds to fatten up a bit, take into consideration when you cut significant amounts of the plant off she will go into shock and take a couple days to a week to get back to normal growth.
my 2¢