Chestnut trees don't produce any nuts during their first few years. If there is at least one other chestnut tree nearby and the trees remain healthy during these years, they should eventually produce nuts.  Chinese chestnut trees usually produce nuts after five years. American chestnut trees usually produce nuts after eight years. Chestnuts usually ripen around early October and drop off the burs they grow on once the weather cools.  You can usually harvest the nuts by simply collecting them off the ground as they fall. If animals tend to grab the fallen nuts before you can, another option is to cut off the burs before the nuts drop. Carefully cut the unopened burs during early to mid October and keep them in a root cellar or similarly cool place. Once the burs naturally open, you can collect the nuts. Wear heavy rubber gloves when handling the nuts and burs to prevent yourself from getting scratched or pricked. If you want to use the nuts for culinary purposes, keep them in their shells and store in the refrigerator for one month. You can also keep the nuts in a freezer for roughly six months.  Chestnuts have a high starch content and do not store as well or as long as many other nuts. After cooking the chestnuts, you can only store them in the refrigerator for three or four days. If placed in an airtight container and stored in the freezer, however, cooked chestnuts remain edible for up to nine months. If you want to treat the nuts as seeds instead of food, you should let them dry in a cool, open space for several days before storing them in a refrigerator. Place the chestnuts in a plastic bag filled with slightly damp sphagnum moss, peat moss, or sawdust. Seal the bag with a twist-tie and store it in your refrigerator.

TL;DR in Indonesian:
Bersabarlah. Kumpulkan buah berangan ketika berjatuhan. Masukkan buah di dalam lemari es atau freezer. Simpan buah berangan untuk digunakan sebagai biji.