It's not really my time line. Mitose told others that he started teaching some select students as early as 1936. And he told some others a different story. But you will find that a lot when dealing with Mitose.
In a 1958 interview with Bruce Haines (author: "Karate's History and Traditions" Tuttle Books, "Karate and it's Development in Hawaii to 1959" University of Hawaii, ), he told Haines that he did not return to Hawaii until 1940. But in another interview in 1960, he gave the year as being 1936. And that it was the bombing of Pearl Harbor, on Dec. 7th, 1941 that convinced him to start teaching self defense to the masses at the Beretania Mission in Honolulu, in 1942. So this is what he told Bruce Haines in 1958 and 1960. Yet Thomas Young told me in a interview in 1988, that they started in Mitose's garage in 1941, and didn't move to the Mission until "after the war", 1946.
And Mitose did teach, at least sporatically, long past 1946. Paul Yamaguichi was promoted to shodan by Mitose in 1952. And Bobby Lowe was promoted to shodan by Mitose in 1953. Arthur Keave, was also promoted to shodan by Mitose in the early 50's.
As to Trias and Mitose. Many have questioned Trias's accounts of his early training in the Soloman Islands during World War II. This is a description of the Solomon Islands during WWII.
World War II
Some of the most intense fighting of World War II occurred in the Solomons between 1942-45. The most significant of the Allied Forces' operations against the Japanese Imperial Forces was launched on August 7, 1942 with simultaneous naval bombardments and amphibious landings on the Florida Islands at Tulagi and Red Beach on Guadalcanal. The Battle of Guadalcanal became an important and bloody campaign fought in the Pacific War as the Allies began to repulse Japanese expansion.
So, many historians of the Japanese/Okinawan arts have asked how it was possible for Trias to be training in boxing and martial arts, and taking leaves to Hawaii, in the middle of some of the fiercest fighting during WWII.