for flower you dont want to interrupt the dark cycle. if you are doing to 12/1 for veg and sticking to that system. you want to be doing 13/11 for flower, and taking 30 mins off the on time every week.
so 12.5/11.5 week 2, 12/12 week 3, 11.5/12.5 week 4 etc..
doing what you are doing now is...