Im certainly not an expert, but I dont think you can "overfeed" it. If I am making a bowl of preferment, I'll pull out about a 1/8 cup of starter from the stock bottle, place in a bowl, and add up to 1/2 cup of flour and 1/2 cup of water at a time, and repeat roughly every 8 hours until I have my preferment active. Whatever amount of viable culture left in your bottle will grow into/feed on however much flour and water you add. What is the purpose of adding flour a tablespoon at a time? and then increasing from there once you see its active? what is the benefit? In my mind, if its alive, it will grow into whatever you feed it, so you might as well give it enough to feed on.