Thank you for reaching out to ask2.extension.

Lawns need a minimum of 1inch per week.  With new grass, it will be easier on the grass for the first weeks, especially with summer heat, to water more often.  If this were my lawn I would consider watering more often at least through September.  The better start before winter, the better survival rate you will have.  As with anything, your circumstances will tell how often you water.