Above 0C, I just drive off gently for the first few kilometers.
-15 to 0C, I might idle it for 30 seconds and then drive off gently for a few kilometers.
Below -15C, time based on temperature. At -30C, I'll let it run 5 minutes, but thats more for the transmission.
My daily driver is plugged in when it is below 0C for a couple of hours before I head out in the morning.
The Porsche gets proper warm-up times, especially in the spring or fall as it uses 20W-50