Another option to consider might be year-to-date instead of individual months. Monthly achievements are sporadic, depending on when trials occur in a particular geographical area (the only reason my dog and I show up on the May leaderboards is because we just happened to start the month with a three-day double-run trial). Year-to-date results, on the other hand, would track cumulative progress towards year-end placements, which is probably what most people are interested in anyway.