The smallest quantity of power that I can supply in this setup is 19.35V during 1/255 of 1/490 second. If smoke starts signalling within that period, I can't ramp up any easier than that.incandescent bulbs have a very low cold resistance and only reach rated resistance when at full temperature. What you experienced with an initial over-current shutdown due to the startup cold bulb resistance is not uncommon. If you want to stay with a voltage mode for your bulb you could slowly ramp up the voltage, that should keep the initial current lower.
I thought of relaying to a parallel warming up circuit. But for that I would need a high power low-ohm resistor that wasn't in my box today. The additional 5 ohms of the relay itself wasn't sufficient.
But hopefully it is solved already. The on/off switch is at the bottom of the potentiometer, so it always starts low (if the mosfets are not broken and wide open). For the last few hours it has steadily started flawlessy.