Feed them 1x a week by mixing your nutrients according to a feeding schedule for the age of the plant and the flowering phase...
give them approximately 1 liter of water for every gallon of soil they are in.. do it SLOWLY so it soaks in well- a small amount should come out the bottom of the planter.
DO NOT water again unless the top 2 inches of soil get totally dry, and the planter light... this will depend on the temperature & humidity in your room, and the type of soil you used. Use only water between feedings-- but no matter WHAT yo are giving them, check the pH!!!!
They will not start to bloom until they are in 12/12 at least a week- more if vegged under 18/6 instead of 24/0... Some strains- especially Sativas, can take several weeks to start blooming.
Do NOT start counting the days until harvest until they are actively blooming!