How to calculate the Ji Yue of Beijing according to the festival or the first day?

The four seasons of the year begin with Jiazi Day in Meng, Zhong and Ji, and the four seasons begin with four solar terms.

"Demon Star" from the first day of the first month of each season (Meng Yue); In the second month (mid-month), Jiazi Day began to "confuse the stars". In the third month (seasonal month), the crops are cut on Jiazi Day, and then arranged in the order of the nine planets, and the cycle is repeated.

Good luck.