Although it is not that cold here, I have found a nice way to keep the cabin warm without using too much power.
First, time the preheating to be done as closely to your departure time as possible.
During the preheating, the liquid in the heating system will be heated using the grid power; the goal for the time you are driving is to keep it hot, therefore, use the climate control in AUTO, but at a lower temperature, say 19°C or 20°C. This will still keep you warm but it will not ask for too much power from the pack to keep the liquid hot.
Turn off the climate control at some times by using the ON/OFF button only but not too long to avoid letting the liquid get too cold.
Use the heated seats, it helps to make you feel warmer.
While driving, even if you have the climate control turned off, cold air from outside comes in by your feet (my only complain to Nissan so far). If possible, use the recirculation mode when the climate control is off (but the windows will fog-up and you will have to turn on the defogger for a few seconds every couple of minutes or so) or do like my wife does; she cover her lower legs with a scarf of an airplane blanket.
If it bothers you that the A/C light stays on while using the AUTO mode, then follow this sequence; I do not know if it makes a difference, and I have not noticed a temperature or power consumption difference:
Set the climate control to AUTO
Press the windshield defogger button
Press A/C to turn it off
Press the windshield defogger button again and it will switch back to AUTO with the A/C light off.