Depending on the ratio you are targetting , if you want to harvest with a bit of amber trichomes but not too much then harvest the top buds 1st because even after harvest the trichomes will continue to mature a bit so your final ratio will be around 30% amber.
50% clear 50% cloudy is what most of the growers are searching for so if you harvest now the cloudy ratio will be higher on the final product.
I personnaly prefer a 50%cloudy , 50% amber to sleep good