You really need to monitor your trichomes with a 30x or 60x magnifying glass to know when to flush. Clear trichomes are not ready, cloudy/milky trichomes are at their maximum thc level, amber trichomes are past their prime and converting into cbd and other less desirable chemicals. If you like an energetic high then you don't want any amber. If you want a hard hitting high that sinks you into the couch then you want a lot of amber. I prefer a nice medium and try to harvest with as many cloudy as possible. If you are in soil then it is usually good to start flushing when you have 5 to 10% amber to get a nice balance. It is something you kinda have to play around with to see what you prefer. Good luck!