I still recall when I first articulated my ideas as "libertarian." It was back in the year 1984. (It's possible it was a little earlier, in 1983. I don't remember the exact time, but it was in the time frame of the months before the primaries in Michigan, in 1984.) I was working as a waiter at a restaurant called the House Of Flavors in Houghton Lake, Michigan. Occasionally I'd have political discussions with the restaurant's manager (I'd describe him as a "pragmatic Republican").
One time he said to me, "You're a Libertarian, aren't you?"
I said, "No. What is a Libertarian? I've never heard of that before."
"You should check it out," he told me. "You say a lot of the things they say."
So I did. Next time I was in the town library (this was, of course, in the days before the universal Internet and the World Wide Web), I looked through the card catalog, and found a book containing the text of various political party platforms for the previous few election cycles. I got the book and checked through it there in the library, and, sure enough, there was this political party called the Libertarian Party, and there was the text of their latest political party platform.
I read that platform, and I still remember thinking at the time, "Wow, here's a whole political party that agrees with me."
So in fact I was libertarian in my thinking before I even knew such a word existed, and before knowing anything about any political party based on libertarian principles.