There is a wide belief that the time to sell your house is in the Spring/Summer. If you put your house up on the market in November, it surely will not sell. While there is definitely some credence to the notion that the Spring season can help with home sales, you shouldn't feel that your home is a lost cause if you list it later in the year.
The first thing that you need to think about is your prospective buyer. If you live in a nice neighborhood with a 4 bedroom/2.5 bath home, it is likely that your buyer is going to be a family. A family usually centers it's schedule around the kids, and as such, is more likely to move during the summer before school starts. If they do choose to move during the school year, it will most likely be lateral (within the area). Personally, I live in a more urban setting, with smaller bungalows and young professionals. It is unlikely that a family a five will want to move in to my 2 bedroom home. The person that is buying my home is a recent grad, might have been renting the last couple of years, under 30, etc... I should not feel uncomfortable listing in October.
There are a myriad of issues to consider when deciding to sell your home. While the date is something to think about, it should not be a deal breaker!