Read Acts 1:4-8. 1:4: "wait for the promise of the Father."

In ministry we must know that God is with us in power.  Jesus promised to be with us in power as we make disciples (Mt. 20:28). So the disciples were to wait until their immersion in the Body of Christ by the Holy Spirit (1 Cor. 12:13).  In ministry we do not need to know everything about the job (1:7).  Far more important than a detailed job description is the assurance of God's involvement in my ministry.