the leaves have nothing to do with it. they normally turn yellow due to flowering nutes have little to no nitrogen. a plant is ripe by the trichomes. first they are clear than cloudy and then amber. its all preference when you want to chop most people do 50/50 cloudy/amber but some say that amber is the thc degrading. to look at the trichs you need a loupe or a macro camera. yours is looking pretty close to being done if it is not already. the hairs normally recieed when it is close to harvest time but it is not a true indicator of it being ripe.