If you have a microscope look for milky or amber crystals(trichomes) on the flowers also look for the calyx(a false seed pod) to swell. A general rule of thumb is that 50% dark hairs and it should be picked. The plant can be picked in stages as well.

These budded naturally and are that well developed? What region do you live in? I have some budding that aren't quite that well developed and others that have barely just started.