When should I start watering until runoff?

I agree, plants should be watered to run off each and every time you water, this is the only way you will know that the substrate is wet/moist all the way through. Roots are amazingly long and to have pockets of dry substrate will hinder root growth and possibly kill off beneficial soil microbes that your plant relies on. Take a look at my diary "Holy Mackerel...WTF to see a 6 inch taproot from a 3week old 3 inch seedling that I culled. The pictures should explain why watering to run off is so important for healthy root growth. Follow your intuition when growing and try to not be overwhelmed by too much information overload. "Listen" to your plants and get to know them, rather than worrying about some obscure suggestion that just messes with your mind. After a while growing, you will indeed learn to understand what your plants are "telling" you and "listening" to your plants is what makes the difference between "master" growers and "wannabes"! If you find yourself thinking your plants need more water, then you are learning how to "listen" to your plants. Listening is the key to learning. Hope this helps, all metaphysical and stuff! ...Organoman.