It saddens me to see that people are more interested in "proving when the tribulation period will start and end" than getting people ready for Christ's return. If you do not have a personal relationship with Christ, it will not matter when the rapture takes place because you will not participate in that blessed event. Our objective, as born again children of God, is to bring the gospel to the lost (Matthew 28:19, 29; Mark 16:9-20; Acts 1:8). Our efforts are being wasted on when things will happen instead of getting ready for when they happen. Jesus said that no man knows, not even He Himself, when God will send Him to claim His bride. When the Lord returns is not for us to know. Only God knows that. We must be ready for when He comes. And, we must tell others that they have to be ready also. This is all that matters.