Based on some of the others I looked at, it seemed like the last half of one month and the first half of the following month were getting letters at the same time - so end of June/beginning of July was in September, July/Aug would be October, Aug/Sep would be Nov, and so on. Granted, that was looking at a small number of people who actually reported their dates and stuff, so it could be completely off base... Especially since some obviously don't fit that pattern. But... //shrug//