Some russian толковые словари provide examples of metaphors with голубой, such as Голубые магистрали (о больших реках), Голубое топливо (о газе). Голубой экран (о телевизоре) - such expressions appeared and were quite popular in Soviet journalism and my guess is they appeared after 1923 (considering Russian history, for example history of television). Such expressions were used roughly through 40s - 60s (I can just guess here), so perhaps even at that time this new meaning was unknown.