yeah this is one question you wont just get one answer too...
yet no one can really explain when they should be done... I have looked into a few posts and the general consesus is...
regarding when to harvest herbs..
Harvesting Herbs
Herbs should be harvested when the oils responsible for flavor and aroma are at their peak. Proper timing depends on the plant part you are harvesting and the intended use. Herbs grown for their foliage should be harvested before they flower.
- Harvest early in the morning, after the dew dries, but before the heat of the day.
I have personally noticed the plants look like they are dripping wet about 30-60 mins after the sun hits them in the am