The lunar calendar takes November as the second month, December as the ugly month, and January as silver moon. Followed by Uzuki in February, Chen Yue in March, Mitsuki in April, noon in May, moonless in June, Shen Yue in July, unitary month in August, garrison month in September, and 10 sea month. But unlike December, it is marked by 24 solar terms.
In this way, as long as you know when your birthday is in the lunar calendar, you will know the earthly branch of your birth month.