It depends on what variety you have. Some are sterile, others produce fruit but they turn out to be empty little balloons. I've had some that are supposed to produce but they only make nasty pithy fruits that didn't contain any seeds. You'll be able to tell if a fruit will develop as soon as the bloom withers. I can't remember how long it took the fruit on my vines to mature, over a month, I'm sure and I don't recall if different varieties took different lengths of time.
Karyn