As the others said please post better pictures next time. But 12 weeks on an auto should be fine to harvest. I'd recommend getting a jewelers loupe for a closer look at the trichomes. Once they are all milky/cloudy with about 15-20 percent amber you're good to harvest. There are plenty of articles online about indicators for harvest but you definitely don't want to harvest too late or too soon. Your grows look great so keep it up!