First off, thank you to all for your help and comments.
My AD put me in touch with its Patek rep who told me today he recommends correcting the annual calendar settings at noon (after the time the moon-phases makes it daily move) and including the day of correction when counting the number of days since the last full moon. My only problem now is trying to determine when the disc is exactly in the middle!
Thanks again for the help. I've learned a great deal from this forum, and I am thrilled that I now have a reason to participate.