You're going to get a lot of different answers here. I'll give you mine:
Don't change a thing. What got you to the point where you (presumably) have a healthy plant and are about to harvest has worked just fine. Just like in nature, the soil doesn't suddenly pull back nutrients because plants are aging, you needn't do it either.
I grow in hydro, where I'm monitoring nutrient levels twice a day. I found that my plants stopped taking nutrients on their own in the last three weeks. All I had to do was add water, and the nutrient levels stayed the same. In a sense, the plants were "self-flushing" if you want to call it that. That's also why I was getting that beautiful fade on the leaves up top by the buds. The plant itself stopped taking nutes and was pulling from the fan leaves. (Another reason not to cut them!)
So MY advice -- and it's just mine -- is don't change anything about the plant's environment that has been successful up to this point. If the plant doesn't need nutes, it won't take them.
When your trichomes indicate that it's time to chop (I go with 5% clear, 90% cloudy, 5% amber because after hanging I'll probably be at 10% amber), then do so. But I disagree with the earlier poster who said all you have to do is worry about the cure. You have to worry about drying first. I believe in a slow dry -- somewhere around 10 days. Then a jar cure. I follow the advice in the Harvesting & Curing section, where you keep the RH between 60 and 65% for as long as you can.
Between a proper dry and a proper cure, you're looking at another 6 weeks of work or so.
Now a thousand people will chime in with advice that completely contradicts mine. That's fine, to each his own. Good luck!