Flowering is actually when i start lst .After a week of 12/12 when the plant has nearly doubled in height i loosly tie down the main stems ( i top) to the side of the pot , what happens is the main stems stop growing up for a day ,and then start growing in a U shape as they try and grow back towards the light , while this has happened the lower branches have caught up in height and voila ,a little cannabis bush.. then it is simply a case of doing the same to any tops that are getting higher than the rest .Just don't do it if you feel your stem is a bit woody or might brake ,you will know the difference between a nice plyable stem and one that will brake anyway just by feel.