I have hatched as early as Jan. 9th, and it was cold, and I was brooding in our unheated garage. If you are careful and can keep them warm, go for it.
I do not like to do fall hatching, in fact, I don't like to hatch anything for myself after about May because I want my birds to be close to full grown as they can get, and possibly laying, before the cold starts coming. I find late hatched (anything in Summer or Fall) will grow slower once it starts to cool down. Rather than their energy going into development, it shifts to surviving and keeping warm. They will catch up, usually, but they take longer to mature. That is my personal experience.
However, I did hatch 6 Silkies in October that are doing great, but they have been in an insulated and heated brooder house with heat on them since day one. It barely dropped below freezing in that building even with a window cracked this year when we were at our coldest. If I run more than one heat lamp in that building, it is like a sauna in there if there are a bunch of chicks in it.
So, if you can accommodate them to keep them warm during the cold months, then hatching can be done any time.
I also do not use broodies because either they go broody when I am finishing my hatching or they are doing it when it is still freezing cold and I don't have a place to put a broody hen and chicks unless I put them in the brooding house, but my rule with that building is that once they leave, they don't come back, for biosecurity reasons.
- Senora Pollo Loco