assuming everything is already pulled out of "storage" (every nook 'n' cranny around here) and it's ready to go, it takes me 3 full days to set up. typically I put out the hard to steal / stay outside stuff the weekend before the big day, and then spend all day on halloween putting up all the other props, smoke, and light, etc.
this doesn't include previous testing of lighting and all that stuff the month before.