m0useanswered grow question 3 years ago Advanced Nutrients recommends the following:
Use 2 mL per Liter during the last week of the bloom phase.
https://www.advancednutrients.com/products/flawless-finish/
I'd be inclined to use it the way they advertise it.
But with all nutrient companies you can get away with half doses if its needed.
Some people just flush with ph'd water vs using and flushing agent. Its all personal choice.
Best of Luck and Happy Growing