The procedure I usually follow:
1a - Turn sound system and A/V distribution on - We actually have an A/V extender setup, so as soon as the extender setup is powered up with the sound board
1b - Computer on (laptop for us) and log in to computer
2 - Plug A/V into laptop - Linux on my laptop will detect the HDMI cable plugged in, then setup the extended display setup for me automatically
3 - Start OpenLP
4 - Use OpenLP Projector Manager to connect and turn projector on
5 - Setup service
Works for us.