I see many different stages of growth. Some 4 weeks away, some 8 to 10. Am guessing it's a Sativa/Indica hybrid. If these pics were all taken at the same time I would suggest you are heading for a split harvest.
This is where decisions can be tough in an outdoor grow, depending upon your climate/frost danger.
The two extremes of a split harvest are as follows.
You can cut half (the mature half) down, expecting to cut the rest down a couple of weeks or later. The trouble with this is it tends to 'shock' the plant and the 2 weeks you were expecting becomes 4.
The other option is to harvest about 20% of the buds at a time, 4 or so days apart. Shocks the plant less.
Thes timings are very approximate and this is just to give an idea of the theory. It also depends on growth habit, light, variety etc. Your own situation/climate will have more of an effect than anything. It's whatever is best for you.