Orange Spot in first set of leaves

Your plant won't have N deficiency in its first week of life.You are already giving nutrients so N deficiency is out of question. First single blade leaves with those spot on them is something I encounter in every grow because I put them directly under HPS lights which make the room a little bit hot and first set of leaves are very sensitive to it. But , it always disappears after second set of leaves because plant gets over the stress by itself,means there is nothing to worry about as you watch the light distance. This is a heat + light related temporary problem.I entered the topic knowing exactly what you asked,before looking photos. This is a common thing that won't affect the plant growth. Your plant has already 3rd set of leaves in only 7 days,great progress so far. If it was N deficient,you wouldn't have seen this much growth.Watering regime looks good too,no worries.