I wish we would have started ours on a night cycle . But due to other circumstances we have them off from midnight till 6am . But next cycle we will be off during the hottest part of the day .
You could slowly adjust your light cycle so that it becomes night time. Simply change the on off time by 1/2 hour or 1 full hour every day.I don't believe that the one hour difference will cause any harm to your girls.
For the record I also prefer a night time cycle. I have complete control of light in the room so I can afford to be dark during daylight.