two or three days in the shade should harden them sufficiantly. Never give nutes to a plant as young as that one is if planted in soil. It has barely established a good root system and gets plenty of nutriants from the soil for its needs. I personally harden mine for a good week before I put them into the ground to lessen the shock of exposure to direct sunlight. A little more sun each day and at the end of the week they go into the ground. As far as nutes go I have seen more harm caused by overzealous feeding then by underfeeding. I don'r even think of feeding them until week 6 or so of their life, and then only 1/4 or 1/2 strength for the first feeding. If you have decent soil, then you should have no problem going without additional nutes until the plant uses up what is already in the soil, then a vigourous feeding schedule can be used.
good luck with your grow