Originally Posted by
JDNSW
Well, actually I am not strictly a naturalist, although I suppose in nineteenth century parlance I could be described as a natural philosopher. (geophysicist)
The word you are looking for is naturist, and your mistake is why I prefer the word nudist - they have the same meaning, but the latter is less likely to be confused with a totally different word.
OK, having had my fun, to answer your question, somewhere around 25 years, although there was no instant decision, no single event I could point a finger at. Probably the first time I was nude on a public beach was in 1983.
John