Why did Zhang Wansen's short message arrive after 10 years?

Because the hostess will end her journey at 6: 30 pm on the day of the college entrance examination and return to 10 years later, she received a short message from Zhang Wansen. SMS is his circulation mechanism.

The main line of the story is this: Lin Beixing was abandoned by her boyfriend who had been in love for eight years on the eve of her wedding. When collecting old things, she found an old mobile phone used in high school. The hostess mistakenly deleted a short message and returned to the college entrance examination ten years ago, but at 6: 30 pm on the day when the college entrance examination ended, she would instantly return to real life. Later, I finally learned that Zhang Wansen fell from the lighthouse at 6: 30 pm on the day when the college entrance examination ended, which is why Lin Beixing ended his journey and returned to ten years later. So the hostess searched for the cause of death of the hero again and again in the reincarnation of time and space.