Depends on what you'd mean. I had been crushing on strong women since early adolescence, but Wonder Woman and Elly May Clampett were the usual inhabitants of my fantasy life.
The first time I saw a female bodybuilder was when one did a routine on the Johnny Carson show. This would have been early to mid 1980s, so I would have been in my early twenties. I think the woman who was on there was Georgia Miller Fudge, but I've never been able to confirm that. I do remember she was blonde, tall, and busty, and made quite an impression.