Once one of the fruits falls and feeds the animals, most, if not all of, the remainder of the fruits on the tree are harvestable as being mature. Then they can be picked, hard, but fully yellow in color, and ripened on the countertop in the kitchen. Or, you can do a bag of some sort, usually mesh (as in the mesh bags that you might get onions in) and allow the fruit to fall into the bag without hitting the ground. Most canistels have to very, very soft before they reach full flavor.
Harry