Foiliar feeding during flowering

I have read alot of different things about foiliar feeding during flowering. My baby is starting to show different bud clusters now and i have heard both that u should and should not use foiliar feeding during flowering as it can wash of the resign when it is sprayed???? who can guide me to the truth????

Also i was wondering if it is best to spray the plants, whether it be with nute's or water alone when the lights are turned on or after they are turned off??