Grass seed

Water twice daily, or more if it is really hot out. You cant really overwater the grass seed. Avoid letting the soil dry out. When the grass is around 4-5" long you can mow it, but mow it a tad higher than the normal grass height you normally mow at. After 4-5 weeks, it can be re-fertilized with a general starter fertilizer to aid the growth of the young grass. After a month or two (depends on the grass type) you can mow it at a normal height & treat is as normal grass. As with any grass, you can still mow it to keep it in its healthy green state. 

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Sod

For the first few weeks/month, more care must be taken to ensure the future health of the sod. Depending on the weather, you will need to water the sod more. If its above 75 degrees, it will need more water generally, and if the temperature is below 60, it wont need as much water as often. You must water the sod to the point where the sod itself is of course soaked, but also so that the soil underneath is wet. During the first 5-7 days of watering, the soil should've soaked up a good amount of water like a sponge, which means you can reduce the heavier watering patterns. You can lift up an edge of the sod to see if the soil is wet, which means it has been watered heavy enough. Stepping on an area and slightly sinking in means it has enough water too. If the edges of the sod are brown or cracking, it means you are not watering it heavy enough.

 

So again, after 5-7 days, you should be able to (unless its the middle of a super hot/dry spell) reduce the watering frequency, as the roots will have trouble wanting to grow if the soil is constantly over saturated. Since you were doing heavy watering in the morning and evening for the first 5 days or so, you can maybe now do a normal watering in the morning hours, and then a light "drink" in the evening hours, if you deem it necessary that is. You should be able to get away with doing once per day for the following weeks, especially if its cooler weather and also if it has been raining as well.

 

You can mow it when it gets a bit high, just like you would with already-established grass. For the first cut or two, maybe keep the cutting height higher than normal to reduce stress on the grass. Another thing to keep in mind is to not mow after watering, as you will make indents in the sod/soil. Plan to mow it many hours after the watering, or else before you water it. Starting around week 2-3, the soil should become more firm as it settles and the grass roots thicken. Around week 3-4, normal mowing habits can be made on the sod, but still be careful to not make too harsh of turns with the mower, as you may risk lifting up the sod if its isnt quite rooted yet. Leaving clippings is suggested, as it does produce nutrients to the soil as they break down, but this is up to you. Once established, your sod can be watered once a week or on an as-needd basis as with any lawn.