The Day of the Lord begins as the Tribulation period commences. It continues through the 1,000-year reign of Christ, because the renovation of the world by fire afterward is still called the Day of the Lord (II Peter 3:10). Some try to make this the Rapture confusion. It begins immediately after the Rapture. This is the reason that the Day of the Lord comes as “a thief in the night” — I Thessalonians 5:2.