In Stage Two, Chapter XXVII, Pip receives a tardy message from Joe, who asks to visit Pip.  And, even though the message, written by Biddy, expresses Joe's wish that Pip "excuse it [the visit] for the love of poor old days," Pip has these feelings about Joe's visit:

Not with pleasure, though I was bound to him by so many ties; no, with considerable disturbance and some mortification, and a keen sense of incongruity  If I could have kept him away by paying money, I certainly would have paid money.  I had little objection to his being seen by Herbert or his father, for both of whom I had respect; but I had the sharpest sensitivenss as to his being seen by Drummle, whom I held in contempt.  So throughout life, our worst weaknesses and meannesses are usually committed for the sake of the people whom we most despise.

When Joe arrives, Pip confesses that he wants to run away as he recognizes Joe by "his clumsy maner of coming upstairs."  After Pip greets Joe, the man who has been both a father and a friend to him, is askward and clumsy in the London lodging.  He places his hat on the mantelpiece only to have it fall.  As he tries to converse with Herbert, Joe fixes his attention on the recalcitrant hat that topples again, making a comedy of Joe's efforts to appear polished.  He becomes so nervous that he his eyes "attracted in such strange directions," he coughs, and sits so far from the table that he drops much of his food.  Pip remarks,

I had neither the good sense nor the good feling to know that this was all my fault, and that if I had been easier with Joe, Joe would have been easier with me.  I felt impatient of him and out of temper with him.

After the meal as Joe takes his leave, he tells Pip that he will not return to London as he is "wrong out of the forge."  Realizing the simple dignity in Joe, Pip hurries ashamedly out after him after he recovers himself, but Joe is gone.

Well, there are plenty to choose from, but I will talk about the first signs we have of Pip changing because of his "Great Expectations" with regard to his relationship with Joe. One key factor you need to bear in mind is the method of narration in this novel. It is called retrospective first person narrator, which means that it is an older Pip who is looking back at his life now that he is wiser, and writing down the story. This means, though, it is sometimes difficult to distinguish when we see the older Pip writing, and when he is merely recording the impressions and thoughts of the younger Pip. Bearing this in mind helps us as readers be aware of how the older Pip is very critical at times of his mistakes as the younger Pip.

For me, the end of Chapter 18 is the start of this change in Pip that you relate to. He is so enraptured and caught up in his new Great Expectations that he is deaf and blind to the unhappiness that Joe and Biddy feel about losing him. Pip decides to only put his new clothes on in town as he does not want to wear them as he walks through to town and have everyone starring at him. When Joe, very fairly, remarks that there are people who would like to see him in his new suit, Pip replies:

"That's just what I don't want, Joe. They would make such a business of it - such a coarse and common business - that I couldn't bear it myself."

Later on he is unforgiveably rude to Biddy, but then, with a note of strong irony, he says that he "handsomely" forgave her for what he saw as her impertinence. Here we see the beginning of the development of the snob that Pip is to come, and how he sacrifices his relationship and love with Joe because of his wealth. We see here that Pip is now ashamed of his humble origins, not wanting to show people who formerly were his superiors and betters his new clothing.