Storylink Interview: Robert McKee
His discussion of "Inciting Incident":
In terms of Inciting Incident, to name just two of its many principles, Placement and Effect are interrelated, mutually influential, and dependent on the writer's subjective sense of function.
One, Placement: The Inciting Incident radically upsets the life of an empathetic protagonist. Therefore, do not waste the audience/reader's time. Bring the Inciting Incident into the story as soon as possible.
Two, Effect: But do not introduce the Inciting Incident until it will have its full emotional and intellectual effect on the audience/reader.
When is that moment? Who can say? In every story it is different. How much understanding of setting, history and character does an audience/reader need to know prior to the Inciting Incident so that when it arrives it will have its full effect? In some stories nothing; in some stories a lot. How and when will an audience/reader fall into empathy with a protagonist? In some stories immediately; in some stories never; in some stories somewhere along the way. The answers to all these questions require the writer to develop a rich intellectual understanding of their story world and its characters as well as a deep subjective sense of the feelings, textures and emotions flowing within the story and outward to its audience/reader. There are no rules. All artists who wish to write must stop thinking that way.