Timing light operation question

[92470]

Can anyone tell me if you are supposed to dial the advance degree dial on your timing light to what you are trying to hit, like 8 degrees BTDC and then adust timing. Or are you supposed to dial it to 0 and then adjust timing?

I bought a used light, and can't figure out which to use it. Today I dialed it to 0, then adjusted my distributor until it was 8 degrees BTDC on the tab like the factory spec says. It seems to run O.K. But I could also dial the light to 8 degrees and adjust my distributor to 8 degrees on the tab and it seems to run alright that way also? Any advice is appreciated. Thanks