We planted our first seeds 3 weeks ago (and consider it a little late, but not too late). Our next batch of seeds is going in this Saturday. We do plant squash in the winter - gourdes, butternut, pumpkins.... and also we did some experimenting this summer and it worked out good becausee we still have tomatoes!!!!! and some plants are young and will hopefully keep produceing for a while. we also plant (in the fall) beets, carrots, chard, spinach, greens of any kind.... also our pepper plants are still going and our leeks (which we planted last march)...
I think if your soil 'looks' good you can take a chance but if you have had anything growing in it recently or if it is that dull tan color you will need to turn in some composte and maybe some peet... its worth the money for good soil otherwise your efforts and money on water and seeds will be for naught. We buy soe composted dirt from Home Depot and also the miracle grow dirt is good.