Harvesting ready buds only?

hey guys, pretty new to this site. my 1st grow is coming to a close, and i want to harvest the topmost ready buds and hit the smaller, weaker bottom buds with some more light to increase yeild. im running a DWC bubbler, and and plan on flushing a week or so prior to harvest. my ? is, once i've flushed and harvested, how long can i keep the plant growing? should i hit it with more nutes and grow a couple more weeks, or only let em go a couple more days? i normally dont ask, but i cant find and answer anywhere...

thanks!

Yes, it's fine to do that. Main colas do finish earlier. Lower growth, in my experience, can go a full two weeks more or less after the tops are removed. Keep an eye on your trichomes!