It depends on what your growing in...... If its soil (promix), then you dont water as often (maybe once every 2-3 days), if its Coco, you water daily.... I personally use coco.... You water WITH nutrients 6 days per week..... Then on the 7th day, you use PH'd water ONLY to give them kind of a flush... Any runoff in coco is waste, so you get rid of that with a drain or wet vac... You cant over water coco as long as you do it correctly... This promotes the most VIGOROUS growth Ive ever seen in my life.... Im talkin, like 30% faster and bigger and healthier than soil.... Sure you waste some water and nutrients in that overflow, but the finished product is sooooo much better... As for the best time to water..... It is right when your plants are waking up.... So about 30 minutes after the lights come on, feed....