Oh?
I think folks can repent at any time they choose.
Agreed, however when it comes to nations and human nature - the biblical chronology is often exactly as II Chronicles 13 & 14 lay out.
A people usually are not willing to repent of wickedness before they are chastised.
Given the Osteenification of the church in America, the concept of repentance I am told is Old Testament and was replaced by Grace.