When is the date of the awning?

The date of the awning is June 5-7 in the Gregorian calendar every year, and the time of the awning is not fixed. For example, it is June 6th in 20 19 and June 5th in 202 1. Mango is the ninth solar term in the twenty-four solar terms and the third solar term in summer, which is of great significance in agriculture. The lunar book says, "Fighting refers to the past."