I reduce my feed levels during the last couple weeks, precise amounts and timing are based on individual plant needs.
There is no NEED to flush if you weren't feeding to the point of massive salt build-ups, the belief is that it strips the flowers of the plant of their stored nutrients and chlorophyll. I'm anxiously awaiting a study that proves a plant releases chlorophyll or anything else from its flowers simply because it doesn't have the nutrients it needs to properly photosynthesize, take in water, or perform cellular functions. I dont smoke leaves, and that's where the nutrients are pulled from to try and keep the plant healthy. So I'm unsure of any benefit flushing has for the flowers themselves.
If you have 25% amber, its probably time to pull IMO. You didn't mention medium that I saw, so it could vary, but give them a few days to a week or so of reduced nutrient levels, they just don't need that much towards the end. People who flush usually disagree and pump their plants full until the day they start flushing, then claim it's necessary to get rid of the extra salts they just put in.
If its time to harvest and you havent reduced or flushed, dont worry about it. Just harvest and make sure to get a proper SLOW dry and cure. I trim wet so my buds dry faster than those who trim after drying, but Ive done that once and never will again. I set up a humidifier and reduced airflow instead. Aim to have them hang dry for about a week or more, then straight into jars if you want, or paper bags/mixing bowls for a day or 2 before jars. If you get a hygrometer youll be able to tell precisely how dry your buds are. My process is as follows:
~1 week hang dry in 60-65*F, 60-65% RH
~1-2 days in bags/bowls
~Into jars, usually around 75% humidity in the jar
~1-2 weeks to reduce the buds from 75% to 65%
~Cure at 65% for as long as I want, burping once a week until I pull them out of cure or they reach 55%
