What does Wemmick advise Pip to pay attention to when he eventually goes to dine with Jaggers?

Wemmick advises Pip to look at the housekeeper.

In Chapter XXIV, Pip talks with Wemmick prior to "diving" into the city, and Pip tells his new friend that he has been invited to dinner at the home of Mr. Jaggers. In response, Wemmick advises Pip to look at the housekeeper. Curious, Pip asks, "Shall I see something uncommon?"

"Well," said Wemmick, "you'll see a wild beast tamed. Not so very uncommon, you'll tell me. I reply on the original wildness of the beast and the amount of taming. It won't lower your opinion of Mr. Jagger's powers. Keep your eyes on it."

In Wemmick's taciturn manner, he reserves comment upon this housekeeper, simply encouraging Pip to observe and form his own opinion of the woman.

When Pip dines at the house of Mr. Jaggers in Chapter XLVIII, he notices a most intent look on the face of the housekeeper as Jagger's speaks of Mrs. Bentley Drummle. As he peruses her face, Pip thinks,

Surely I had seen exactly such eyes and such hands, on a memorable occasion very lately.

As he continues to study the woman's hands, Pip notices that she makes a knitting motion with them. This triggers Pip's memory of watching such a hand wave from a staircase or a stagecoach: "And i felt absolutely certain that this woman was Estella's mother."