My first look was "The Lights of Zetar" in prime time. It was probably the NBC repeat, summer of 1969. On a black & white TV. I was too young for that episode. The technician's big death scene was too much for me.
But I was ready for it when the show went into syndication, the following year or so. I was all about the afternoon reruns. It would be ten years before I voluntarily missed an episode, and that was "And the Children Shall Lead." And it was for a death in the family. What could I do?
Everyone should skip "And the Children Shall Lead". Always.