The average grow takes 4 months including drying and curing. That means typically most plants will be ready to harvest in 10-13 weeks depending on if the right conditions are present. If you don't know how long they have been growing, you really should keep track.
Having said this as an outdoor grow the first indicator would be the lower leaves start turning yellow and falling off. Judging by the pics I'd say another 2 weeks at least. The trichomes are clear right now and should be milky in color when ready. All the pistil hairs should be curled in too.
Just remember, drying and then curing the buds properly will make it smoother and more potent. Patience...it looks like a good plant with plenty of buds don't screw it up but rushing the process.