In America the dinner hour is not a fixture, since it varies in various sections of the country.
The ordinary New York hour when “giving a dinner” is eight o’clock, half past eight in Newport.
In New York, when dining and going to the opera, one is usually asked for seven-fifteen, and for seven-thirty before going to a play.
Otherwise only “quiet” people dine before eight.
But invitations should, of course, be issued for whatever hour is customary in the place where the dinner is given.