"As soon as man fell, Christ entered on his mediatorial work. Then it was that he began to execute the work and office of a mediator. He had undertaken it before the world was made. He stood engaged with the Father to appear as man’s mediator, and to take on that office when there should be occasion, from all eternity. But now the time was come. Christ the eternal Son of God clothed himself with the mediatorial character, and therein presented himself before the Father. He immediately stepped in between a holy, infinite, offended Majesty, and offending mankind. He was accepted in his interposition; and so wrath was prevented from going forth in the full execution of that amazing curse that man had brought on himself. It is manifest that Christ began to exercise the office of mediator between God and man as soon as ever man fell, because mercy began to he exercised towards man immediately. There was mercy in the forbearance of God, that he did not destroy him, as he did the angels when they fell. But there is no mercy exercised toward fallen man but through a mediator. If God had not in mercy restrained Satan, he would immediately have seized on his prey. Christ began to do the part of an intercessor for man as soon as he fell; for there is no mercy exercised towards man but what is obtained through Christ’s intercession. From that day Christ took on him the care of the church, in the exercise of all his offices.
He undertook to teach mankind in the exercise of his prophetical office; to intercede for fallen man in his priestly office; and to govern the church and the world as a king. He from that time took upon him the care of defending his elect church from all their enemies. When Satan, the grand enemy, had conquered and overthrown man, the business of resisting and conquering him was committed to Christ. He thenceforward undertook to manage that subtle powerful adversary. He was then appointed the Captain of the Lord’s hosts, the Captain of their salvation. Henceforward this lower world, with all its concerns, devolved upon the Son of God: for when man had sinned, God the Father would have no more to do immediately with this world of mankind, that had apostatized from and rebelled against him. He would henceforward act only through a mediator, either in teaching men, or in governing, or bestowing any benefits on them." (Jonathan Edwards, History of the Work of Redemption; underlining mine--CD)
Presumably Edwards would profess belief in the Biblical teaching that the intercession of Jesus Christ is ALWAYS EFFECTUAL and that Christ is ALWAYS heard of His Father, etc (John 11:42; Hebrews 7:23-25). A brief comment here is that Edwards profanes and perverts the particularity and unfailing efficacy of Jesus Christ's Mediatorial work. [cf. A.A. Hodge on the Priesthood of Christ]