Completely depends on what you want from your smoke.... "normal" is when the trichs have started to transition from clear to cloudy but before they start to become amber - this gives a a rounded and enjoyable high, neither too heavy nor too cerebral. "Late" harvesting - when trichs are amber - will give you more resin and a heavier sedation effect... but timing is crucial as this runs the risk of the THC content degrading.
It also depends a lot on the strain you're growing....
Best advice is to test your grow to see what YOU like... harvest some early, harvest some at the "normal" time, and harvest some late... then, when you grow the strain again, you'll know what worked best for YOU...
Good luck!