Hi Chris, I hit an error when I replied to your message, so I am pasting my reply here.
Sorry, I can't improve on "around 1960".
Here is the story of my involvement with the cult. In 1955, my final year of school (Jeppe Boys High) I read "Dianetics: the Evolution of a Science" in Astounding mag, and got hooked. I found "Science of Survival" at the library, and got more hooked. Then I saw an ad in the paper for a course in Dianetics and Scientology, by Keith Gerry. I didn't know what Scientology was at this stage. Anyway, I visited Keith at his office in Safric House, Eloff street, and started to learn about Scientology. Keith gave me a free course of processing because he wanted to practise "Six Levels of Processing" before using it on his paying customers. Another Scientologist, Ken Cameron Gunn, had his offices in the same building.
In September 1956 I attended a Hubbard Professional Auditor course run by Jack Horner and Margaret Scholtz. This was at 27 Hancock street, which was then the offices of Tom Gormley, a naturopath. Margaret later married Tom. Other HPAs at the time included Ray Stout, Ron Colley, Jerry and Lila McGillicuddy. Over the next couple of years I did some refresher courses, and then Jack and Alison Parkhouse and Harriet Yeller came out and ran a B.Scn course which I attended. This was in late 1959. Shortly after this they set up the HASI , and all the local Scientologists were upset and felt that would ruin the scene.
About this time Keith Gerry went to Saint Hill to do a D.Scn course, and when he came back he declared that Hubbard was insane, and he started making plans to go to India and look for a Guru. But I don't think he ever went. He is now in the UK, involved with the NorthConnex railway scheme and wind flow around tall buildings (He was an aeronautical engineer).
In 1963 I had a argument with a friend undergoing psychoanalysis, and suddenly realised that all my arguments against psychoanalysis applied equally to Scientology. So I went to HASI and asked to see some evidence. They immediately declared me to be an SP, and sent a letter to all my Scientology friends telling them not to communicate with me and to use any opportunity to do me down. My friends just laughed this off. I guess I was one of the first, if not the first, SP in South Africa. But I still have my Founding Scientologist certificate! Before HASI messed up the scene, most of the Scientologists were searchers, still involved with Yoga, Theosophy, and other spiritual techniques. All "squirrels" in Scientology lingo.
I once saw Hubbard in person, having a conversation outside 27 Hancock street. I heard he was in South Africa trying to buy land in Rhodesia.
That's about all I can recall. Hope some of it is of use to you.
Cheers,
Mike