I'd say by the time I harvest there will be hardly any leaf left
fan leaves start to dry up and die off towards the end just before you harvest. as long as the buds look good, i think your ok. if your doing inorganic fertilizer, do 1 last nutrient session 2 weeks before you chop. if its organic, you can stop 1 week before.
if your using miracle gro (like i was), you might go through a magnesium deficiency since it doesnt contain any. i put 1 tsp of epson salts it in a gallon of water along with my last session of nutrients and they looked a ton better after 3 or 4 days.