re: When did the definition of creole change?

The meaning changes depending on point in history and place. In New Orleans, it originally meant the first generation born in the New World, generally French and Spanish. Creole was usually synonymous with wealthy, educated white people, again, who were French and Spanish. As (usually) French masters had children with African slaves, those children were also Creole. They had all the rights of their white half brothers and sisters. The right to be educated and to inherit land and money. There were white Creoles, Creoles of color and free people of color. After the Civil War, the meaning started changing again...

Cut to today in southwest Louisiana when Creole is often associated with black French cowboy culture.

There's a whole lot more to it, of course.