To my knowledge that is what is happening…catabolism of chlorophyll (the green disappears) and other molecules in the leaves as a last ditch effort to obtain nutrients for flower production.
As a beginner i’m going by trichomes…about 5-10% amber developing and I start planning on letting the medium dry out, then chop chop time. My other indicator is once budding has slowed, not many new pistils being kicked out (which goes in line with the plant drinking less). Great info on this thread for me to think about though!