Don't flush, do not listen your friend. it's a myth, go search in google and u will find lots of researchs about it. Flush is bs. Keep ur feed, probably feed more at the end, like 800ppm to 1400ppm depending on lights or co2 in the room. Just make sure u are not wasting ur nutes , cause the plant convert everything and its not like elements like iron and cobalt in soil cause u are growing indoor. so, if u are using good nutes , organic nutes don't bother listen tour friend. U can cut whenever u want. Also...no need to wait x many days in darkness...it's another myth. good luck