The other reason Amon insisted on making a move the day after the jailbreak was that it was the first day of the week. During that day, the Prime Minister held a weekly meeting with the royal family and important kingdom officials to discuss kingdom matters. The mayor was among the officials who joined the meeting, and it usually lasted a whole day. In addition to the issue of the recently occurred jailbreak, the meeting would be even longer. They would probably leave the palace way past midnight.
In the mayor's absence, the person with the highest cultivation inside the city hall was absent. That person was the mayor's bodyguard. He had the cultivation of the Intermediate Spirit Stage. The mayor himself was a Peak Mystic Stage cultivator.