First ever grow

A few tips. If I am reading this right, you are using a mix of soil with coco and perite right? The first tip is to keep an eye on your temperatures, if they get below 73F (23C) the growth rate will be very slow (not your case); second, watering, at this stage, only give a cup of water every 4 days, why? to force the plant to make a strong root zone and additionally if you give any more the plant will become waterlogged and it will have trouble getting oxygen through the roots (this makes the plants growth slow down to a crawl), only increase the amount when you notice that the media dries faster. Third, check the light to plant distance, 30 inches could be too much decreasing the light intensity that your seedlings are getting, try putting it closer, but mind that the heat is not too much; there's a simple test you can do, place your hand at canopy level, if it is too hot for the back of your hand, then it's too hot for the plants. Fourth, train your plant, as it grows try to get an even canopy so all tops receive the same amount of light, google LST or TOPing and try to learn to do it. Good luck mate and patience