I just checked Machig's Complete Explanation (I probably should have done that before.) After I quick look through I found, "Every [lunar] month [observe] these four dates: the first, the tenth, the twenty-fifth, and the eighteenth. Also these three: the fourteenth or the twenty-ninth, the new moon, and the eighth or the fifteenth. On these seven days, get up early, and once you've done prostrations and polished [the shrine], arrange the three supports and light incense..." (p206)
So, of the three days mentioned on the KTD website, only the 29th is mentioned, but I have something else to do on that day, too.
Oh well, I might just do it when I feel like it.