Spring is a great time to install sod as the ground is moist from the spring thaw and the temperatures are cooler so the sod can better establish itself before the heat waves hit.
Your sod will have a better chance of surviving if planted in the spring than in the summer.
Don't forget the key to establishing a good lawn is ensuring it has enough water.
Watering in the early morning is much better than the night before as watering the night before can cause mold and mildew issues in you lawn.
Never water your lawn in the middle of the day either as the water droplets will act like thousands of tiny magnifying glasses burning your lawn.