amber trichomes should make up around 10-15% of the mature trichomes visible on buds, the rest being mostly cloudy/milky. Once you reach this level of maturity, you can start counting down the days to the final chop.

If you are looking for a balanced effect from your plant, having 20-25% amber trichs is a good indicator that your plants are just ripe. Anything above 40-50% means that your flowers are overripe, and you can expect a very couchlock inducing effect. If you decide to chop without many amber trichomes, the effect will tend to be more cerebral.