What is the point of Esther, Ada, and Richard spending a night at the Jellybys'? What does Dickens accomplish with this break in their journey toward Bleak House?

The stated reason for the break in their journey is that it would be too long a journey to continue on to Bleak House. The Jellybys represent a lifestyle and social class that Esther, Ada, and Richard are unfamiliar with. It is disorganized, dirty, and chaotic, which may also represent their introduction into the Jarndyce case. It also serves as a convenient means to introduce several characters who will become participants in the story, like Caddy Jellyby, and Mr. Guppy. Mrs. Jellyby is oddly, a woman so obsessed with philanthropy toward a foreign country that she neglects to show any at home to her children, an irony that Dickens wants to emphasize.