When I used to go out in service in the morning, if it appeared that the householder might not be up yet - curtains still closed, no sounds coming from the house - I'd knock lightly so as not to wake them up. Just loud enough that they could hear it if they were in their living room. However, quite often this would backfire....I'd knock lightly and then I'd hear 4 or 5 large dogs inside going berserk, which would in turn get the next door neighbor's dogs barking too.
Many witnesses I worked with wouldn't care if the householder was obviously still asleep. They'd pound on the door extra hard. Their reasoning was, "If your house was on fire, wouldn't you want your neighbor to wake you up? Well something worse than a house fire is coming," referring to Armageddon. I'd explain to them that their reasoning will only offend and antagonize the householder. It would be better to make a note of the address and return at a later time, such as Sunday afternoon after the meeting. I would always remind them that we come uninvited and therefore we need to be considerate.