It's kinda hard to tell. Do they feel "papery" or are they turning brown at all? If so I'd harvest them. Also, crush one in your hands or split it open and take a whiff and look at the lupulin glands, you know, the double-yellow-line-on-the-road yellow part at the base of each petal. I know I'm in dire need to get my harvest picked and dried. I was going to yesterday but got bogged down trying to fix my trellis. Nine bines make for a pretty heavy load.