If you look now, you'll see that generally from now to 2 months forward there is availability opening up on and off. This has been a trend for a long time. I would say it's likely that November availability will open up starting in August/September. It helps if you're flexible. If you're eyeing super high season time (Thanksgiving), that's probably not going to open up until a couple days out at best.

I'd say if you're feeling lucky, next 2-3 days always seem to be available whenever I look, even over holidays.