Everyone was assembled at the appointed time.

全体人员均按规定时间召集到场。

《牛津词典》

Results may be realized at the appointed time.

按时见效。

《新英汉大辞典》

I arrive at the appointed time.

那天我按约定时间准时到了。

youdao

He was flabbergasted when at the appointed time, the lady who had been cleaning his office walked in.

FORBES: Briefing Book: A. Michael Lipper

When I arrived at the appointed time, I saw the tissue box and knew.

FORBES: Bouncing Back After A Lay-Off

If a business associate explicitly promises to meet with you at a specific hour and always shows up on time, you expect or trust he will appear at the appointed time at the next meeting.

FORBES: The Fed Undermines Trust In the Dollar