When was the Old Testament program changed?
The Old Testament program changed when Israel rejected the King and the Kingdom, and Jesus was crucified and returned to heaven, rather than immediately coming after the Tribulation. This ushered in a waiting period of 2,000 years while Israel was set aside and the Church Age occurred.
Les explains that the Old Testament program had Israel receiving the King and the Kingdom, after which they would carry the knowledge of salvation to the Gentiles. But that program was changed when Israel rejected the King and the Kingdom and Jesus was crucified. Instead of coming immediately after the Tribulation, He returned to heaven to wait 2,000 years while Israel is set aside and the Church Age takes place. Les notes this was not revealed in the Old Testament; nothing indicated a 1,900-plus year period where God is not dealing with Israel. It was part of the secret God had not yet given.