Ooh interesting, nobody else has mentioned starting at #4! I did purposely make all the words orthogonal on the off-chance somebody would. I wonder if anybody will start sooner than that... I suspect #3 is the earliest possible (with its small green hint in the printable version).
Poetic considerations aside, "The word searches are done / _______" would actually be counterproductive since the checkbox is for the players who just found "as you now have won" and thought that was the whole message. I might revise the checkbox message to "Fill out 12th word list" or "Write 12th word list" or something. (I assume you found the full message since you mention the "meanings of the even-numbered leftovers"?)
(By the way, I reduced the listed total from ___/150 to ___/144 in v1.18 so that players like JoePlaysPuzzleGames won't worry that there's 6 secret words if they forget about Puzzle 0. And to give stuck players a hint that there are 12 groups of 12.)