She's ready........there are no hard and fast rules when it comes to trichome color that is 100% reliable for 100% of cannabis strains.
I have had strains that produce 70% amber trichomes from about the third week of flowering, to other strains that have barely any amber, 5-10% max, after 10 weeks of flowering.........it all comes down to genetics.
Once you have 100% brown pistils, the plant is getting closer to death, so don't wait too long until harvest.