What is the purpose of delayed emergence and how is it portrayed in Moliere's Tartuffe?

In Moliere's seventeenth-century farce Tartuffe, the playwright does not formally introduce the title character until the second scene of the third act.  Writers sometimes use this method, generally called delayed emergence, to achieve certain effects within their works.  The delayed emergence of Tartuffe serves a very particular purpose for the audience.  Though Tartuffe does not actually step on stage until the third act, he does play a formative role in the first two acts.  

He is frequently the topic of the conversations among the other characters.  From these conversations, the audience begins to develop a certain set of expectations of that character.  The characters object to the fact that Orgon is so concerned about Tartuffe's well-being, specifically his food intake.  Orgon makes these inquiries after finding out that others are not eating well (heavily indicating that Tartuffe's eating habits are affecting others' diets).  It is this ostentatious show of wealth (the ability to eat well) to which others object.  Tartuffe, in their views, is devoid of the humility characteristic of religious ascetics.  In addition, the reader learns a great deal about the other characters.  Ultimately, while delayed emergence can allow the reader to form opinions about Tartuffe, more often the reader forms a perspective on the title character crafted by the author.

Tartuffe is depicted as a character who is all talk and very little substance, causing most of the characters to be suspicious of him.  Only Orgon treats him with any respect.  When Tartuffe enters in the third act, his emergence only intensifies the views the readers form in the first two acts.  The first words out of Tartuffe's mouth amount to his calling for his hair shirt and scourge.  As a self-professed religious figure, he should know that wearing a hair shirt and a scourge are not public affairs.  They are worn beneath one's clothing and not meant to be seen.  When he speaks to Elmire in the same scene, he insists she cover her bosom out of propriety.  He does not show true religious devotion.  It is for show, and everyone knows it.