The cycle has ended and you buds are already over mature. Time to harvest your beauty. Don't worry about the yellowish leafs...what is happening is that the cycle ended and the grow doesn't have anymore the metabolism to keep integrating nutrients. As I told you by the colours in your buds, you must harvest today if it is possible your grow, otherwise you will start to swap the THC to CBN and you are just turning your yeld over narcotic due to the CBN. Good crop, mate! 420