But the Lord knows. That's more important than our knowing. He is busy preparing a people who will be prepared to greet Him when He comes. Just as God prepared the people of Israel for the first coming of Christ, so He is preparing the world for His second coming. With the Lord, there are no surprises.
Surprises are great for suspense novels and murder mysteries.
But when it comes to our Lord's coming to judge the living and the dead, there are no surprises. You are all sons of the light and sons of the day. It's no surprise. The apostle is speaking to all believers in Christ, all who take His words to heart. We know that Christ is coming, at any moment.