When does the Bible refer to the tribulation as the actual wrath of God?

Les explains that always remember this, the Bible does not refer to the tribulation as being the actual wrath of God until the last three and a half years. He points to Revelation 6:17, "For the great day of his wrath is come," as the verse that marks this. This means the earlier part of the tribulation is not called God's actual wrath; only the final three and a half years are.