It's unknown when Haas first encountered Charles Fort.  Given his reading habits, it could have been as early as 1919, when Fort published his first book, or the mid-1930s, when he reached the acme of his fame and science fiction writers began to take serious notice.  Dating his activities as a Fortean is a little--although not much--earlier.  In 1966, he wrote Clark Ashton Smith's then-widow that he had been collecting Forteana for twenty years.  Generally, in areas it is possible to check, Haas's recollections have been reliable.  So that means he was an active Fortean starting just after World War II, which is consonant his deepening activities in fandom.  Certainly, he was a dedicated Fortean by 1953 when he met Clark Ashton Smith, for the two talked of Fortean things that day he made the trip from Oakland to Auburn.

Around this time, Haas also became acquainted with other Forteans.  Robert Barbour Johnson was one.  The San Francisco writer Miriam Alan de Ford and Berkeley editor Anthouny Boucher were as well, although there is no evidence that Haas knew them well.  (He may have through Johnson, however, who did know both de Ford and Boucher).  Other Bay Area residents interested in pulps, science fiction, fantasy, and weird tales interested in Fort included Kenneth MacNichol, Polly Lamb (who practiced a form of magic very much like Haas's), Anthony and Phe Laws, and Garen and Kirk Drussai.

In the early 1950s, these and several others started to meet at Kenneth MacNichol's writing Studio, Pencraft, in San Francisco, to discuss Fortean things.  Johnson, whose memory is not to be trusted, said in the 1970s that the meetings were at first twice a month, then monthly, and that around fifty people attended.  They called themselves Chapter Two, acknowledging that Tiffany Thayer's group in New York City was chapter one.  The group discussed individual meetings and discussed local Fortean happenings.  (Johnsosn says that there weren't many, because the UFO craze had not yet started, but of course that began in 1947.  Another instance of his poor memory).

The group broke up sometime in the middle to late 1950s.  Johnson says the late 1950s, but he also dates its demise to the death of the founder, Kenneth MacNichol, who died in 1955.  Certainly, by the early 1960s, Haas was telling Smith's widow that the group was disbanded.  And his interest in Forteana seemed to decline until the late 1960s when he started investigating Bigfoot.