Pick a day of the week...any day. We chose Friday and call it "Fertility Friday". Easier to remember.
Our objective is to be consistent in providing fertility to growing crops.
Be careful though, because more is not better.
We only want to provide the amounts of nutrients that are needed (in available quantities) and that can be used by the plant, or else we can create imbalances (which can make us feel like the wheels came off the wagon).
We have a number of tools we can use to get closer to the ideal fertility quantities.