A bit of yellowing and browning is expected each year as the tree produces new needles, some of the oldest will naturally fail. this is exaggerated with newly transplanted evergreens. A starting point for watering is about every 7-10 days, depending on soil type and drainage properties of the soil. Those plants have a limited root system right now so monitor the water in the soil in the root ball and immediately outside of that. When it is time to put the hose away for the winter, water one more time.