whe do i start the final flush?

hello,a question im neding answers for if possible. when do you no it is time to stop all the nutrients and give your plants there last 2 weeks of only water to flush? this is pretty much all im concerned about now,everything else i have found advice for on this site- top notch! im worried that i may carry on feeding with nutes for too long and then ruin it all on the final hurdle.any help please!

I've read you can go as early as two wks before you plan on harvesting to 5-7 days. I'm doin it right now with mine!