When did the imperial calendar of China people begin to spread to the people?

The spread and popularization of almanac among the people was after the Song Dynasty.

At that time, an examiner found that most scholars had written the date wrong when reviewing the test paper.

When I asked why, I realized that scholars studied day and night and could only calculate the date according to the astronomical phenomena, so it was very common to miscalculate a day or two.

So the examiner called the imperial court and asked imperial academy to compile almanac every year and sell it to scholars to master the time.

As a result, the almanac was distributed to the people by the court and became the almanac of the people, which has been passed down to this day.