I would think a more rigorous approach would be in order, viz: begin where you last knew you were current. Note the number of posts from there back to the first MOAB post. Subtract this number from the total number of posts as shown in the posts listing. Read forward this number of posts OR read forward until you encounter a single empty posting box.

Enter an annotation into the posting box which either method will reveal, to the effect that you have encountered said posting box and the time at which you did so. This should provide a more stable point for future MOAB displacement metrics.

A