Here it is, 4 months after setting out the plugs. It's a lawn, it's green, and it's not stressed by the temps hovering near the 110°F mark. It was 112° when I took the picture and scurried back onto air-conditioned safety.
Every sprinkler system is a bit different, so the first thing to do is measure the water delivered in 15 minutes. It's the "tuna can" method explained here. Small pet food cans also work. Any container that is flat-bottomed, straight-sided, and a couple inches deep will do.
Lawn Water Calculator for Phoenix. The tuna can method will also reveal any over- and under-watered spots.
After measuring how much water was in each can, I entered the measurements into the calculator. The calculator is based on watering every third day - not optimal for Bermuda, but many people have a problem watering less often. At least it's better than watering every day.
According to the calculator, if the lawn were established Bermuda, It should be watered for 15 minutes every three days. I'm watering
The lawn is not mature - the vendor of the Buffalo grass told me it will use less as the root system goes deeper. He also said that UC Verde is the only one of the buffalo grass cultivars that truly thrives in heat. That's good, because Phoenix has had temperatures mostly above 105°F for the past couple of weeks and there's no relief in sight.