I normally set the table an hour before the guests arrive .. after I have done all the safai in the room, thats when i do the table ... as its one big task out of the way ...
Always before the guests arrive, sometimes an hour before sometimes the night before. I cover the plates/table with a cloth to prevent any dirt getting on them. But actually probably don't need to, as my dining table is in an airtight conservatory so as long as the windows are closed, its all good.
I usually set the table with tablecloth/napkins/runner the night before....plates in the morning upside down.Cutlery and glasses about an hour before...any decor like fresh flowers ten minutes before guests expected.Think that's it...