when was the nevuah of shabbos chazon given?

חֲזוֹן֙ יְשַֽׁעְיָ֣הוּ בֶן־אָמ֔וֹץ אֲשֶׁ֣ר חָזָ֔ה עַל־יְהוּדָ֖ה וִירֽוּשָׁלָ֑‍ִם בִּימֵ֨י עֻזִּיָּ֧הוּ יוֹתָ֛ם אָחָ֥ז יְחִזְקִיָּ֖הוּ מַלְכֵ֥י יְהוּדָֽה׃

Rashi and other meforshim explain that the opening pasuk of chazon is an introduction which tells us that Yeshayahu prophesied for the duration of the reign of four kings.  The Metzudah puts it succinctly:

בימי ארבעת המלכים האלה ניבא עד שעמד מנשה והרגו.

When was this particular nevuah that we read on shabbos chazon given?  That's not clear.  At the end of Rashi in parenthesis there is a comment that says it was given at the end of Chizkiyahu's reign, but there is no justification for that claim given nor it is clear that the comment is even from Rashi.

Malbi"m has a different pshat.  He writes:

חזון ישעיהו נבואה זאת נבא בימי עוזיהו ושנה אותה בימי כל מלך ומלך.

The first pasuk is not telling us historically how many years Yeshayahu prophesied for, but rather is telling us when he gave this specific prophecy -- namely, he gave it in the days of Uziyahu, and then again in the days Yosam, and then again in the days of Achaz, and yet again in the days of Chizkiyahu.  Again and again Yishayahu went around giving the same exact message, hoping that this time, in this king's reign, someone would finally listen! 

Yishayahu may have been killed by Menashe, but he is still giving us the same prophecy and the same message, year after year, shabbos chazon after shabbos chazon, hoping someone will finally listen.