GeekDavid
Auror
Here's some input from K.M. Weiland's Outling Your Novel (which includes a lot more than basic outlining):
What Is an Inciting Event?
Bestselling legal suspense author James Scott Bell describes the inciting event as a doorway: "The key question to ask yourself is this: Can my lead walk away from the plot right now and go on as he has before? If the answer is yes, you haven't gone through that first doorway yet.
What Isn't an Inciting Event?
Your story may include several important plot developments before you get to the inciting event. For example, in Ridley Scott's 2000 film Gladiator, the inciting event -- the death of Roman Emperor Marcus Aurelius -- doesn't occur until after several important scenes, including Aurelius's offering his throne to the protagonist. Even though the preceding scenes are important, they do not irrevocably change the character's world.
Where Should the Inciting Event Occur?
Generally speaking, the inciting event should occur not quite a quarter of the way into your story. Setting it this late in the story allows you to appropriately pace the introduction of your character, his personal problems, and his normal world, so readers will sympathize with him and understand when the inciting event blasts into view. For example, Gladiator's inciting event takes place after the character's normal world has been established (via the opening battle and the main character's interactions with the emperor and other important characters).