Where do you live?
What kind of grass do you have?
If it was not sodded, what variety of seeds did you use?

Any organic will work fine. The application rate is 20 pounds per 1,000 square feet. My favorite organic right now is alfalfa pellets (rabbit chow). You can get it at any feed store in 50-pound bags. The "slow release" feature means that you should not expect to see an improvement in color, density, or growth for 3 full weeks. But then you should see all three.

NPK is completely meaningless in organic fertilizers. With organics you are looking for protein content. The higher the protein values, the better the fertilizer. At the highest end is corn gluten meal and soybean meal. At the lowest end is ordinary corn meal and used coffee grounds. Alfalfa is in the middle and a pretty good one. Organic fertilizers provide food to the soil microbes. Then those microbes process the food and convert it to plant food. It is a biological relay process, so that's why it takes 3 weeks.

When you write back, if you have a bermuda or St Augustine lawn I'll have more to say.