Hi there.. unless you're on hydro (nutrient-solution based without another medium like coco), then i'd say stop watering about 2 to 3 days before the chop. This way the plant gets stressed a bit, as it thinks it's dying and will still produce a bit more resin in the final phase. Whether you want to go for full darkness that's up to you. Some swear it works, while others say it doesn't.
What i would do in regards to harvest is to cut her at the end of a dark-cycle, so just before the lights come on.
happy harvest!