When my neighbor uses my system, he whirlpools going through the counterflow chiller (water on) until the whole batch is cooled. Then a rest for about 10 before cast.
I prefer to whirlpool through the chiller (water off) for 8 mins then rest for 12. Start cooling water and cool as I cast, monitoring output and controlling wort flow rate to control the temp.
Summer in Georgia only lets us get to about 80 using straight city water with no other tricks. Using either technique, the time is about the same.