The question asked is the fastest time. According to the problem, it can be 10 seconds per day, which is easy to understand. So June 16 is fast in the morning 150 seconds, and it is 30 seconds fast in the daytime. As long as it doesn't get to night, time won't slow down, it's fast 180 seconds.

This is the earliest time to reach 180 seconds.

If the day passes 16, the time will slow down after nightfall.