You know, October is turning out to be a very tricky month to predict! I know everyone wants to find a magic window of time when the parks will not be crowded, but it is getting harder to identify that window in October.
Now don't get me wrong - this doesn't mean that it will be absolute madness all month long. Lots of people think October is a great time to go because of lowER crowds (not low crowds, just lowER). Others say that when they went in October it was too busy for them to want to go back. But that's pretty much the case with any month - some people will think the crowds are outrageous, while other folks will think they are not bad at all.
There is no denying that HalloweenTime has gotten much more popular over the last few years and it's not really the same 'off-peak season' that it used to be. But you can still have a great time if you go in with the right expectations, plans and preparation in place.
Based on all that I have either experienced first-hand or read from the many DIS'ers who share their stories here, for a while it seemed that the general, informal 'rule' of sorts used to be that the first half of October was very busy due to Gay Days, various school breaks, Columbus Day, etc. I'm not sure that things are any different now - it seems to be more or less the same.
Then, around mid-month things would taper off a bit and the crowds would drop slightly.
But in the week leading up to Halloween it gets really busy again, as people with multi-day trips culminating on Halloween night arrive at the Resort.
So it would seem that right around the middle of October would probably be the least busy - at least, that was the case. Some of the school breaks are inching closer into mid-month, though, so it's hard to say.
Just as a point of interest, I received a PIN code offer with special rates for the hotels, but it only covers 10/16 - 10/31. A few other DIS'ers have gotten the same thing. To me, the fact that the offer only covers the second half of October is a clear indication that Disney expects the first two weeks of October to be very busy. Usually, they do not offer the really good hotel discounts for weeks in which they expect big crowds. They don't need to offer discounts for those weeks because they will be booked up anyway. But they will trot out some offers for weeks when it is not as crowded. So I have a feeling that DLR may assume that the first 2 weeks of October this year will be very busy, while the second half of the month will be less so. Perhaps that is what happened last year and they are assuming history will repeat.
As for the party itself, Tuesday nights will probably always be less crowded than Fridays or Halloween night.