NOTE: Hopefully you have adjusted sprinklers before seeding to insure even amounts of water over your newly seeded area.
For instructions see:
Lawn Watering Guide
for California
Turf Watering Guide from UC Davis:

1. Set sprinklers watering duration (length of time) so just the top ½-1inch of soil is watered, there are no roots yet so you want to target area where seed membrane is, topper, seed/fertilizer, top surface of soil.

NOTE: Usually 2-3 minutes is sufficient  depending on type of sprinkler, water pressure, tempeture and wind. You may need more you may need less:

2. You may need to set up to 4 watering periods (times per day) to keep seed membrane moist this will depend on many factors, time of year, outside tempetures, length of days, wind, to name a few. 2 to 3 times per day is normal, but long summer days or above normal heat may require more. While shorter days, cooler temps, rain will require less or not at all.  Most important is not to let seed dry out once it takes up water and the life cycle starts it can’t dry out or it will die before it gets started. Try to avoid standing water or if you see moss or a black slime your are definitely overdoing it or maybe there’s a problem with a sprinkler/sprinklers or poor drainage. Try to figure it out. Good even watering is the best, sometimes you may even need to break out the hose to “spot” water a specific area to fill in gaps, no system is bullet proof, you need to be the farmer and nurture your crop.

NOTE: Continue this watering schedule until complete germination of area is achieved. 7-14 days.

3. After 7 days late spring, summer, early fall your seedlings should start to rise thru the topper reaching for the sky. Sometimes taking up to 14 to 30 days in the late fall, winter or early spring. As seedlings start to mature and roots and leaves stretch  you will need to the adjust the amount of time for each watering period so water goes deeper to nourish growing root systems, again adjust per conditions (weather), maybe 5-10 minutes or more per watering period. 7 days after germination (14 days total), you might have to reduce the times per day you water, if you are at 4 make it 3 if you are at 3, make it 2, at 2 make it 1.

4. Grasses like deep watering, less often as a rule, so as you reduce the amount of times per day you water continue to increase the length of watering period. EXAMPLE: Sprinklers watering 3 times per day at 3 minutes. Take out middle watering period and increase morning and late afternoon periods to 6 minutes each. Then after another week or 2 take away the late afternoon watering period and increase your watering time again for your morning watering period, say to 12 minutes. Then after another week or 2 start taking away whole watering days, (start with every other day), if you see plants start to get a grey green appearance or will not bounce back after you step on it then you need to increase your morning watering time till it can make it through the day and still hold its color and resiliency. You should be able to keep cutting back on the times per week you water by increasing the amount of time per watering period. EXAMPLE: Set sprinklers to run every 2nd to 3rd day and run sprinklers long enough to make it through till the next irrigation day. Most grasses use up to 3 inches of water per 10 day period on a yearly average to maintain a healthy stand of turf.

NOTE: Check the output of your sprinklers: then adjust water run times to match those flow amounts. Or do it by eye, looking for stress symptoms like grey green appearance and not bouncing back after stepping on it, the the grass will let you know how much and when it needs.

5. As plants roots mature they will follow the water. By not irrigating long enough for water to penetrate deeper into the soil the roots will stay shallow reducing the amount of water and nutrients available to plants. Making it hard for plants to go through a full day without being watered again. By watering for longer periods less often we encourage roots to spread deeper into the soil profile seeking water and nutrients being stored by soil particles deep enough not to be subject to evaporation by sun or wind. Conditioning root systems this way will develop deeper healthier root systems and a much healthier greener "drought tolerant" lawn. So as grass plants mature keep cutting your watering times per day while increasing the amount of time you water per watering period. Roots of Tall Fescue plants can sometimes penetrate up 3 feet down!

NOTE: Best watering times are between 4:00am & 7:00am.