Single lead O² sensor warmup time?

A smog tech told me that my new O² sensor "isn't warming up fast
enough," which I term as being complete nonsense. At issue is that
the car runs open loop until driven under power for a short time, at
which time car goes to closed loop, the solenoid duty cycle closes up
a bit and the ESC II system blocks vacuum transducer-caused advance at
idle. It evidently provides more advance at idle in open loop to
promote better driveability due to fairly lean mixutre when cold
provided by the feedback solenoid in the main jet. This guy says that
the O² sensor should be fully warmed up and giving signal voltage in
three to five minutes after a cold start even at idle; I say he's
confused with later, heater-equipped O² sensors. The replacement O²
sensor is from Bosch. Comments, especially from smog techs?

By the way, the car passed with nearly the lowest dyno emissions for
that model/year in the state's database, so obviously SOMETHING'S
right here!