When a real estate agent calls and wants to show your house “at 3”, he means some time starting at 2:30 or so. To make sure the house is ready to be shown, get the agent to agree explicitly on the time. Otherwise a coffee cup is on the dining room table, and socks are on the floor by the bathtub.
On a related note, one of the annoying things about having a house for sale is needing to break down perfectly functional household organization. The media laptop lives in the bedroom; the comfortable office chair lives by the dining table; the telephone and headset live on a movable side table. But for house-showing purposes, the media laptop and the office chair go in the office, and the phone set up gets tucked away in the bedroom, and the headphones are hidden away in the backpack.