I hope you all know the go-to place for all questions about the calendar of primaries and caucuses for quite some time. No question about it; you want political scientist Josh Putnam's Frontloading HQ. More details than you can shake a stick at, along with plenty of good reference materials about the calendar and other presidential nomination info.
Oh, and, today's CotD. Actually, it's a good overview of the major changes in the calendar since 2008; Josh is responding to a Politico story that mentions the possibility of a frontloading stampede during this cycle, and he knocks down that idea. Quick version: when all is said and done, the odds are that the process will once again start in January, not February as the national GOP parties hoped, but will then be more spread out than it was in 2008. Highly useful, and nice catch!