Watering is dependent on several factors including time of year, recent and current rainfall, and type of irrigation/water method being applied. Generally you want to keep new grass saturated for at least two weeks. The idea is to keep the soil under the sod moist as well as the soil that comes with each sod piece. This is vitally important for root establishment.
Water early in the morning to take advantage of the daily start of the grass’s growing cycle, lower wind speeds and to avoid evaporation.
Make certain that water is reaching all areas of your new lawn, regardless of the type of irrigation system you use. Corners and edges are easily missed by many sprinklers and are particularly vulnerable to drying out faster than the center portion of your lawn. Also, areas near buildings, sidewalks, and driveways tend to dry-out faster because of reflected heat and may require more water.