You always want to power up the main speaker amplifiers last to avoid audio thumps when you turn on the mixer. Before the worship team arrives, you should test each microphone and label it s channel position along the bottom of the console. Begin by having someone speak into the main vocal microphone and repeat this process for each microphone on stage. Set the input trim to unity gain. This is the point at which no level is added or subtracted from the nominal signal.
Most mixers have a mark, which identifies unity on the fader and input trim controls.
Check the owner s manual for your particular console for the proper settings.