If your cups have drainage holes, you can set the cups in a pan of water for 20-30 minutes. The water will seep up into the soil and roots. It will also prevent you from toppling your plant with water from above. A picture would help. Technically a plant is a seedling for a month. Are we looking at a 3 day old. New is vague, but my suggestion will work. Just don't leave the cup in the pan of water. Later on you can get away with it, but right now the plant is fragile.