Our butternut squashes took ages and ages to get going - I blame the cold and low light levels. Eventually, by the end of August, they were covered with flowers but, from 3 very healthy vines, we only have one butternut squash to harvest
.... we're going to have it for a very special meal 
However, I'm hoping that the local farm shop will have some organic Crown Princes as they did last year - last year I bought 4 and stored them in the garage, using them up over the winter and we had some wonderful meals. We used the last one at the end of Feb if I remember correctly.