Another great post from Mark Kennedy.
couple quick notes (more gems still in the post):
One of the most powerful ways to start a movie is to pose a question that the audience wants an answer to.
First act of the three act structure is the exposition, getting all the information about the story's world before the Spark/Inciting Incident imbalances things. The audience appreciates getting the info they need as quick as possible so they can jump into the action.