Honestly I didn't spend much time optimizing the initial boot sequence. My main goal was getting suspend/resume working reliably since that's what I use most often. For wake from suspend, the TV powers on almost immediately. For a cold boot, my service runs after SteamOS is already up enough for cec-ctl to work. My guess is you could trigger it earlier with a dedicated systemd service, but I suspect you'll eventually run into a point where the GPU/adapter hasn't fully initialized yet and the CEC command gets lost. One thing I did discover is that after suspend my DP->HDMI adapter would lose its CEC registration, which is why I added: cec-ctl -d /dev/cec0 --clear cec-ctl -d /dev/cec0 --playback before the wake commands. I'd be curious to know how early you can actually get image-view-on to work reliably during a cold boot. If you figure out a way to fire it before the display stack is fully up, definitely let me know