As a rule of thumb, this happens about a month after flowers fade. The best time for gathering fruit is in the afternoon on a sunny, dry day. Rain or dew on the fruit promotes mold in storage. Drop pods into bags, separating each species. Pay close attention to fruit drying in the garden.
Some types shatter, dropping seeds on the ground.
Others fling it across the garden. When pods open, it's time to move into action. Fruit ripens sequentially. Even if you miss the first seeds, you'll get a chance to catch the next batch. To avoid losing any more of your harvest, tie small paper bags over the ripening pods.