I noticed that at some point in the past, the episode of Sazae-san and the day of Eternal September matched. Every Sunday Sazae-san airs 3 mini episodes, and the next one (episodes 6441 to 6443) will be in 4 days:
6760 - x = 6441 - (3/7)x
319 = (4/7)x
x = 558.25
So on September 6201, Sazae-san episode 6201 aired. What an auspicious day in history!
(Actually, according to my haphazard calculations September 6201 was actually a Monday, so episodes 6201-6203 would have actually aired on September 6200. But whatever, that's close enough for me.)
To celebrate this discovery I went back to September 6201 to find some of the most DQN-quality posts of the day.
http://4-ch.net/dqn/kareha.pl/1282481800/11
...yeah, that's all I found. it seemed to be a pretty slow time in DQN history.
Also, it's surprisingly difficult to find information about the episode count of Sazae-san. There's no handy episode list on Wikipedia, though there is a group dedicated to the study of figuring out what Sazae-san will choose in the weekly "Rock, Paper, Scissors" game. I was able to finally find the episode count in a thread on 2-ch.
So yeah.