Every morning first thing see if those yellow stigmas have turned orange, the ratio of orange to yellow will give you a idea of how much growth will continue, once 95% are orange and no more yellow seem to appear the next morning, this is a good Indicator I use in conjunction with trichome cloudiness.
Only thing you will get from a extra week is a week extra of heat radiation reducing the half life of the trichomes,
Over time I've come the experience the personal preference of harvesting 1 week earlier than I normally would, I'd rather smoke at the peak of life cycle than smoking the start of decay.