Heidegger's Bible Handbook: Micah: Chronology

3.  An account of the time in which he prophesied.

Moreover, he prophesied בִּימֵ֥י יוֹתָ֛ם אָחָ֥ז יְחִזְקִיָּ֖ה מַלְכֵ֣י יְהוּדָ֑ה, in the days of Jotham, Ahaz, and Hezekiah, kings of Judah, Micah 1:1.  Therefore, at the same time as Isaiah, Hosea, and Amos, although he began a little later, since those also began to prophesy under Uzziah, the predecessor of Jotham.