What was the basis of God's program in early Acts up to Acts 1:4?
The basis was the Abrahamic covenant, which dealt with Israel first and then the Gentiles. Up to Acts 1:4, no word had yet been given about going to the Gentiles with the gospel of grace. Christ told them to stay in Jerusalem and wait for the Father's promise.
Les explains that as Acts opens, after Christ's crucifixion and resurrection, there had not been a single word yet about going to the Gentiles with the gospel of grace. Everything was still based on the Abrahamic covenant, dealing with Israel first and then the Gentiles. In Acts 1:4, the resurrected Christ commanded the apostles not to depart from Jerusalem but to wait for the promise of the Father. Les notes this sets the stage for Pentecost, when the Holy Spirit baptism would begin, as verse 5 contrasts John's water baptism with the future baptism with the Holy Spirit not many days hence.