This ad from 1926 hints at an earlier existence reaching back to as early as 1920.  Until we can confirm this date, the only concrete evidence of the age of the radio station comes from the date of the first license issued to the station.  It's entirely possible, though, that the Leese Brothers experimented with radio prior to obtaining a license in 1922.

This is what an original Department of Commerce license looks like.

The application that started it all.  2818 Rucker, across the street from Goldfinch Brothers paints, was the site of the first antenna for the radio station, studios, and transmitter.

The key section to note on this license is toward the end. It's questionable whether the Leese Brothers were able to prove their station was in operation at least since August 13, 1912. The Bureau probably forgot to cross this out.  KQW, San Jose was duly licensed in 1912 as a regular broadcaster and is credited with broadcasting the first two-way wireless telephone test in America in 1915.  KQW survives today as KCBS, San Francisco.