First of all, welcome to gardening! You are going to learn so much just by growing any plant and don't worry about mistakes - we all  kill plants but learn from the experience. Osmocote is made to be easy to use so just apply once a year at the minimum or twice a year to encourage more growth  and that's it. The smaller the pot the less you use. The recommended rate is about one tablespoon for a one gallon pot for indoor plants  so a 4 inch container that holds maybe one cup of soil would get just a pinch or 1/8 tablespoon of Osmocote and a six inch pot that holds twice as much potting soil would get twice as much fertilizer or 1/4 teaspoon. You can estimate how much soil your pots hold by comparing them to a gallon size or quart size milk container.   Work the granules into the soil a bit without damaging the roots then water when the soil is dry to the touch.  Don't worry as using a bit too much or a bit too little will not kill your plants. Keep growing, Marianne Binetti