It was already recognized as God’s wrath at the very beginning as we see in Revelation 6.
It begins with the holding back of the wind, the sealing of the 144k and the appearance of the giant multitude “who have come out of the great tribulation; they have washed their robes and made them white in the blood of the Lamb.”
And then the Wrath of God section of 3.5 years begins. No more salvation. Only wrath.
The wrath of God is the entire seven year period. From Revelation 4 the "church" is gone. After finishing with warning the seven churches in chapter 3 after which they are not seen again, chapter 4 starts with "“Come up here, and I will show you what must take place after this.” After what? After the faithful believers are gone from the earth. Those that were not but realized after the disappearance of millions are the "tribulations saints" who then become believers and who are beheaded. The wrath of God begins with the opening of the first seal.