I saw The Man Trap
on the night it premiered back in '66. I was five.
I recall my dad telling me about a science fiction show that was coming on that night. We were relegated to the TV in mom & dad's bedroom because my mom wasn't much interested in watching a "space show."
I saw the opener and the first few minutes of the show, but got bored (remember I was 5). I recall telling my dad "That's great. I'm going to go play in my room. Call me if there are any monsters, or if they shoot their laser guns." (Of course, all space men must have laser guns.)
About 40 minutes later, my dad calls out to me from his room: "Mark! You'd better get in here. There's a monster, and I think they're going to shoot it with their laser guns..."
I ran in just in time to see the salt vampire, Kirk screaming, and McCoy firing his phaser. I was hooked.
Oddly, it wasn't until many years later that I put two and two together and realized that I had seen the first episode broadcast.