how important was that she arrives "too early for visits"?

This have been the explanation for she coming at night in P&P3,
that it was very bad in Regency times to came before the accostumed hours of visit. But would be Lady Cat less rude and incivil if she had come at a later hour, and behave as she does in the novel?

On the other hand, suppose that she was travelling somewhere, and passed by Meryton, because she was bringing a letter from Charlotte, and she visited Elizabeth, and was amiable and polite, would it be important if she come before visit time? (Assuming that it wasn't a very outrageous time, like when they were at bed)