Cherries will not continue to ripen after they have been picked. It is important for anyone who wants to grow cherries that they be ripe before they are picked or else they will be edible. When a cherry is ripe, you can notice the difference in the way it tastes, looks, and feels.
Ripe cherries tend to weight more and feel heavier in the hand than those which have not yet ripened. It is best to pick your cherries before the birds have started trying to get to them, though you will know when it is right judging by how they look. Ripe cherries also tend to be thicker and sweeter than those which have not ripened.