When do we find out that East Egg is old money and West Egg is new money in The Great Gatsby?

That West Egg is new money and East Egg is old money is clear early in the first chapter of The Great Gatsby(Fitzgerald).  As Nick is explaining his new residence, he takes the time to explain the difference.  West Egg is "the less fashionable of the two" (9), but it is nevertheless quite expensive, with places that rent out for the summer season for "twelve to fifteen thousand" (9).  We know this is the...

That West Egg is new money and East Egg is old money is clear early in the first chapter of The Great Gatsby (Fitzgerald).  As Nick is explaining his new residence, he takes the time to explain the difference.  West Egg is "the less fashionable of the two" (9), but it is nevertheless quite expensive, with places that rent out for the summer season for "twelve to fifteen thousand" (9).  We know this is the place for the wealthy by virtue of the rental prices, but we know it is a place for the nouveau riche because these mansions are very large, tasteless, and "spanking new" (9). Across the bay, we have "the white palaces of fashionable East Egg" (10) that glitter discreetly on the water. They were not thrown up overnight, nor are they over the top with tacky features.  Nick seems quite eager to justify his own presence in West Egg, where he clearly does not belong. Gatsby is his West Egg neighbor, his cousin Daisy is a denizen of East Egg, and Gatsby, who has more money than he knows what to do with, does not really understand how large a divide this is.