I know you like odd detail, Thor, so Shostakovich is generally accepted as being the first composer to use a theremin in a score, for 1929’s “Odna” (“Alone”). At the time, he was 23 years old and the theremin was 10. It portrayed a snowy wasteland, and the score is on Naxos, as much brilliant Soviet era music is (see also their Weinberg releases).