Harvesting while there are still a few white pistils, 5% or so, will give you a mind trip sativa type high and not a heavy and sleepy indica stone.
Trichomes do not rust, amber trichomes are a result of polymerization and a thickening/hardening of the resins.
If all the pistils have already browned off, harvesting when there are mostly milky and/or clear trichomes will give you the type of high you seek, but don't wait much longer, and if this is the case (all brown pistils), THC is breaking down into CBD and CBN, which gives the sleepy stone.
My last bit of advice is to follow your "intuition", if it looks ready to you, it probably is.
Hope this helps,..........
Organoman.