Aircraft Flight Operation Regulations Article 215

The operator or the pilot-in-command (PIC) shall notify the ATC unit and the contents of the flight plan, one day before the intended flight.
中文原文 航空器飛航作業管理規則第215條
航空器使用人或機長應於作業前一日將任務內容通知飛航管制機構。

English translation for reference only; the Chinese text prevails. Not legal advice.