If your on day 64, then your probably closer than you think to harvest...Do you have a 60x scope? The trichs will tell you when to harvest....Not all, but most auto's will go amber like photo trichs do when she's done. So if you have a scope, take a look and see if their cloudy lookin. If so, wait till you see 1/3 amber, then harvest...If ya don't have a scope, then try taking a close up pic or look through a magnifier....That's better than nothing...lol...
But the descriptions on your plants are at the most, 65 days...For the most part, these time frames are pretty close...So watch real close from now on!!!