Well, I don't quite remember - around first grade, perhaps earlier... definitely 1970s... Apart from coloring books and connect-the-dot books of Kirk and Spock and slogans like "RED ALERT", I recall the one with the glowing balls as being the first memorable moment - this turned out to be "Return to Tomorrow". This was in reruns, since there was no way to get a TV involved when the episode first aired. Had no clue about TAS as that likely wasn't repeated, but TOS the TV show definitely was repeated...
Didn't know of the movies for several years, which may have been for the best as TMP would have bored me and there's no way I'd have been allowed to see TWOK. But I did see TSFS in the theater, even finding the recap clip show to be fascinating. Yeah, in home video in-universe contexts those clip shows and other things make virtually zero sense. In the theater, back in those days, it was creative, it worked, and it was arguably necessary given the temporal span between movies.
And, yep, I was in AV Club when we received TNG season 1 thin but glossy paper book covers with the cast photo, for which any of those surviving at this point would fetch serious coin on online auction sites... I'll see if I can find the actual one, or as much as I can remember...