I think the concept of Ordinary World is one of the hardest structural concepts to grasp. Alicia's done a good job of explaining that ordinary is not a synonym for dull, and she's given lots of examples of books with strong ordinary world openings.
Because there are problems in the ordinary world -- after all, no life is trouble-free -- and because fiction shows characters in motion via scenes, it can sometimes be difficult to understand exactly when we've left the ordinary world behind and entered the rising action. We start the story with problems, arguments, disasters and events. And the rising action is composed of problems, arguments, disasters and events. So how do we know when we've left the ordinary world behind?
Here's a simple rule: when the conflict is defined, you are out of the ordinary world.
It's not a new ordinary world. It may bear a strong resemblance to the ordinary world. It may even be an identical setting with identical characters. But something crucial will have changed, and that something crucial is the initiation of the conflict.
Think of Gregor Samsa in Kafka's Metamorphosis. He wakes up in his own bed, in his own home, surrounded by the same family members. This is his ordinary world, and none of it changes through the course of the story. Same bed. Same house. Same family members.
Except one morning when he wakes up, something crucial has changed. Gregor has turned into a cockroach. This change defines the conflict, and from the moment of that change, we're out of the ordinary world and into the rising action as the protagonist struggles to resolve the conflict.
You've all heard the conventional wisdom. Start with events or problems. Start your plot right away on page one, line one. Start with dialogue. Hook the reader. This is great advice. Is it inconsistent with the concept of Ordinary World?
Whether you start with lead-in problems, or start with some other method of sketching the ordinary world, or start with conflict in the very first words, you still have to start strong. You still have to show characters in action--though perhaps I should place the emphasis in that sentence on the word show, because it's important to avoid exposition (which "tells") and rely instead on narrative elements such as dialogue and action.
Now, I'm of the opinion that the shorter the work, the less room you have for Ordinary World in proportion to the rest of the story. So a story like Kafka's can start off by defining the conflict in that famous first sentence:
As Gregor Samsa awoke one morning from uneasy dreams he found himself transformed in his bed into a gigantic insect.
You could probably argue that the ordinary world is suggested by the first part of that sentence, but for our purposes, it doesn't really matter. The story launches right into the conflict without changing the setting. It's a great hook, one of the best in the western canon.
Let's compare this to the first line from a novel with a strong Ordinary World, Gone With the Wind -- I can't lay my hands on my copy of this text right now, so I'm quoting from memory and may not have the exact syntax --
Scarlett O'Hara was not beautiful, but men seldom realized it when captured by her charm as the Tarleton twins were.
The first sentence contains two notions in opposition -- a woman who lacks beauty, and men who are captivated. These two notions are not usually paired like this. In fact, we might call it a collision of opposites. It works precisely because opposing ideas are interesting to readers.
What follows is a somewhat lengthy physical description of Scarlett. Why does it work? Because the passage is loaded with contradictions, juxtapositions, and other uneasy bits. We're told her face contains a too-sharp blend of her mother's aristocratic features and her father's florid, blunt features. Another uneasy pairing, another collision of opposites. And so it goes on for a good 200 words or so, with contrasting pairs, with praise and criticism, with anything other than a rote list of details such as you might find on a driver's license.
In any event, it's a strong opening even though such lengthy description is no longer in favor.
So there you have two examples of strong openings, one in the ordinary world of that story and one which defines the conflict. So remember: Ordinary World is not a function of setting, and strong openings are not inconsistent with the Ordinary World.