Strive for PerfectionG 40

If you are reading this before completing your "Marathon" achievement, choose a February (via changing your system clock), and complete that achievement in February. Then continue on to use that same February for this achievement. Obviously with February's 28 days, that amounts to 6-9 fewer total challenges to complete for the achievement. While this is not a huge deal for many of the other Microsoft Casual Games, for me, this translated to a full hour of time that I was able to save.

If you are NOT reading this before completing "Marathon," then simply use whatever month you used for that achievement, as you are already 1/3 of the way there.

If you did your achievements in a very strange way and did Marathon on one month, but got your Diamond achievement on a totally different month... use your Diamond month. But for anyone who hasn't done that... don't do that.