Where is Udon? Are you getting flowers on your tree yet? After lots of rain and cold weather here in Southern California, my grumi (in the ground) is about to explode with flowers, so, for here, it seems like lots of water and cold weather trigger flowering. Mine is against an 8ft wall and faces east, so it’s protected somewhat and doesn’t get full sun. My trees about 8 1/2 ft tall and probably around the same age as your tree. It was in a 25 gal pot last year and flowered but didn’t set fruit, it’s in the ground now so hopefully I’ll get some fruit with this flush. Good luck.