Always start feeding at low rates, if the directions of the product you bought say 1 tablespoon per gallon start with 1/2 teaspoon per gallon. I strongly suggest that you start out with a NPK soil test don’t feed anything until something is depleted( or low). Different products have different NPK ratings start with something very gentle. A product at 20-20-20 is aggressive a product at 10-10-10 is gentler but still start that at 25% of recommendation. There are many kinds of product available. Look at some ads. Some products like superthrive are very very gentle in N but have no P or K. I am an experienced grower I use a product that is 20-20-20, I mix it really light for fresh young plants and ramp it up to full strength over time. When you get to flowering stage you will need a Bloom product with less N but more P and K. You have a lot of product choices to make organic or not. Don’t let the number of choices freak you out. Now is a good time to look at our grow FAQS I the safest thing is just water , then add when the soil is mostly used up.