Abraham was told that there would become a day, a “set time” when he would receive the promise through Sarah. He knew a specific time that was told to him by the Angel of the Lord, and that produced a specific expectation of when the promise would be brought to fruition. This can be the same for us. We can have specific expectation that the promise will be produced in a specific time. We can harken to the voice of God and allow the Holy Spirit to produce in us an understanding of when the promise will become reality in our lives.