The Yin month is after the beginning of spring. According to the Chinese horoscope, the first month of the lunar calendar is only after the beginning of spring. It depends on the solar terms. The Yin month is the first lunar month in the Chinese horoscope.
The summer month is Siwuwei, which is April, May, and June of the lunar calendar; the autumn month is Shen Youxu, which is the seventh, eighth, and ninth month of the lunar calendar; the winter month is Haizi Chou, which is October, November, and December of the lunar calendar