Should I water my new sod when it is raining

New sod needs a lot of water.  If it is down pouring and you feel the lawn is very saturated, you may turn the sprinklers off for the day...or even the next day if it is cooler outside and you feel the lawn doesn't need the extra water.

There is no rule on how much water sod needs.  It needs a lot, but weather conditions can dictate if that "a lot" comes from the sprinklers or from the weather itself.