When is the best time in spring written by Su Shi in Broken Magnolia? why

It can be seen from the beginning of "Ying Chu Jie Yu", "Slight Rain" and "The grass is far and near, but there is nothing" that the most beautiful and best season of spring written in the ci is early spring (or early spring).

Grasp youth in time, cherish the best time in life, eat, drink and be merry in time, and don't regret being turned upside down when you are old.