Q.what is the proper watering schedule for new tall fescue sod lawn after installation (san diego, CA)? and how does it change over
the first week, month etc? thank you

Certified GKH Gardening Expert
This really depends on how the weather is acting. There is no set schedule, unless you know how often lawns need to normally be watered in your area. On hot dry days, you may have to water twice per day, where as cooler days may only need water every 2 or 3 days or so.
It will be very clear when it is established, in which case you will only water once a day during hot or dry times, and once or twice per week when it is mild. You won't water at all when there is rain.
This article will offer some information: https://www.gardeningknowhow.com/lawn-care/lgen/installing-sod-instructions.htm