I don't flush, I feed till the end. Flushing is bro science. Only need for it is if you overfed or trying to correct a nutrient issue.
There's actually a study they did on flushing, article below. In summary, the plants with zero days of flushing had the best flavor and the smoothest smoke.
https://www.rxgreentechnologies.com/rxgt_trials/flushing-trial/