These words at the start of the verse signal that what follows is significant. They also highlight that the book is coming to the end. This occurrence of the phrase “at that time,” as well as the one in Zephaniah 3:20, refers again to the day of the Lord.
19 Behold, at that time I will deal with all your oppressors. And I will save the lame and gather the outcast, and I will change their shame into praise and renown in all the earth.