It is better to say: "We had an appointment at 8h; it's 8h 30, I've been waiting for you for half an hour. "
ມັນດີກວ່າທີ່ຈະເວົ້າວ່າ: "ພວກເຮົາໄດ້ແຕ່ງຕັ້ງຢູ່ທີ່ 8h; ມັນເປັນ 8h 30, ຂ້ອຍໄດ້ລໍຄອຍທ່ານສໍາລັບເວລາເຄິ່ງຊົ່ວໂມງ. "