Source: 1st in Action Comics #6 (1938)
Type: Precursor/The real deal (since retconned)
Though 1953 is too early to fit in the Silver Age proper (starting date 1956), it's hard to think of 1952's Jimmy as anything but Silver Age. His adventures are very much the kind of thing he would get up to through the 50s and 60s. So how many appearances for the Golden Age Jimmy if we don't count any of his 1950s adventures? Rather few. At a guess, less that 25 sporadic stories across 13 years.
Then the Golden Age Jimmy became the Earth-2 Jimmy and was allowed to live a richer, fuller life, but that's really another Snapshot, isn't it?