You want your lawn to have about 1" to 1 1/2" of water per week, depending on the weather, you may need to water your lawn more during the hot season.
How long should I water to get one inch?
We can't tell you that because every sprinkler system is different. However, you can figure it out yourself, take a tuna can which should be 1" (eat the tuna first, of course), place the can where the sprinkler is hitting. And wait until the tuna can has about a half inch of water. The time it took will indicate how long you will need to water your lawn (at least twice a week but no more than three times a week). Remember, the hotter the temperature the more you should water your lawn.