Obviously the same over here. My observation is that for safety reasons to the engine, it runs in kind of stand-by mode for a few minutes at the beginning to heat up material and fluids before tieing it on to the wheels. Then it increases power and works as expected.
We were down -10°C these days. The whole car had been cooled down for about two days. I started with the ICU from the beginning to take the advantage of the ICU warms heating up the car right from the beginning rather than burning epower for that. Again, it started with a slowed down running engine, obviously not involved in driving the vehicle at all. As the bar in the display wasn't moving in effect to the foot pedal push. After a few minutes it seemed having warmed up and took over control. Effect could be seen in the SOC having lost one bar in the display by then. It, then, even took another few minutes before it activated parallel mode within the defined speed range.
The route planned was longer than SOC reach. It would have eaten up the SOC along the way. I ended up with an empty SOC and 6.5 l/100km. That's 2 litres more than on fair mid temperatures. It was just right to start with the ICU right from the beginning. I can't tell if it heats up the batteries in the background too to achieve better performance.
My experience is that the car does it really well considering conditions. A very well thought out system overall.