As a rule of thumb I use water , Water, feed (at 1500 ppm). Unless they are showing signs of wanting more food, I have a super lemon haze that I have been water, feed, water (at 1500 ppm) Marijuana doesn't have a set schedule for watering or feeding just watch your plants they will tell you what they need. Now remember if you are growing in Hydro medium the changes are much quicker than in soil.
But, what the hell do I know I am just a stoner