It is interesting to reflect that Austen's original title of choice for this classic was actually First Impressions. This title helpfully focuses us on all of the first impressions that there are in the novel and how mistaken they can be. When we think of the first clash between Lizzie Bennet and Mr. Darcy in Chapter Three, it is definite that Lizzie does have cause for disliking Mr. Darcy. Let us remember what he said about her within her hearing:
"She is tolerable; but not handsome enough to tempt me; and I am in no humour at present to give consequence to young ladies who are slighted by other men."
So, we can say that Lizzie does have cause to think him a proud man, which is admitted by Darcy himself at the end of the novel. However, where Lizzie's problems lie is that, having consigned Mr. Darcy to the category of proud and arrogant, she is unable to convince herself that he could be anything different, and is happy to believe and be taken in by the deceptions of others, such as Wickham--another first impression that Lizzie "reads" very wrongly.