Ideally, you'd want to wait until the trichomes have started turning from being all cloudy to some being amber... But you'd need to take a MUCH closer look at them (grab a jeweler's loupe or a microscope or zoom your camera in as much as possible and then zoom in on the resulting pic). Pistils turning brown is also a good indicator (some trichs don't turn amber!)... but from your pics here, they're still all white which is amazing given this is an auto... at least I think it is. Look also for your plant to start to fade - the green leaves will start to "fade" to yellow or some yummy autumn colors... If this is a photoperiod, you could have 3 or more weeks left so don't jump the gun and harvest too early!
Good luck!