On April 26, 1920, Paul Whiteman, in preparation for his June engagement at the Ambassador Hotel in Atlantic City, left Los Angeles. He arrived in Atlantic City on Apr 30, 1929. The Whiteman orchestra continued playing at the Alexandria Hotel in Los Angeles until May 7, 1920. The first band members to join Whiteman in Atlantic City were Pingitore, McDonald and Grofe. For the first few days of June, Whiteman and his three musicians played in the Japanese Tea Room in the afternoon and in the Pompeian Grill at night. By June 8, 1920, the orchestra was in full strength.
Here is the first mention of Whiteman in the New York Times June 29, 1920.
https://lookaside.fbsbx.com/file/FirstM ... GbgYFNcGzx
https://www.digitalcommonwealth.org/sea ... :x920gf02d#