I interpret Hebrews 9 to mean that Christ entered into the New Holy of Holies–Mary, the Ark of the Covenant, “Heaven itself”–with his own blood, thus eternally redeeming us. This mystery of the “one sacrifice” would take place both in the Incarnation and at the Crucifixion, and forever.
Is that how you interpret it?
11 But when Christ came as high priest of the good things that are now already here,[a] he went through the greater and more perfect tabernacle that is not made with human hands, that is to say, is not a part of this creation. 12 He did not enter by means of the blood of goats and calves; but he entered the Most Holy Place once for all by his own blood, thus obtaining* eternal redemption.** 13 The blood of goats and bulls and the ashes of a heifer sprinkled on those who are ceremonially unclean sanctify them so that they are outwardly clean. 14 How much more, then, will the blood of Christ, who through the eternal Spirit offered himself unblemished to God, cleanse our consciences from acts that lead to death,[c] so that we may serve the living God!
…19 When Moses had proclaimed every command of the law to all the people, he took the blood of calves, together with water, scarlet wool and branches of hyssop, and sprinkled the scroll and all the people. 20 He said, “This is the blood of the covenant, which God has commanded you to keep.”[e] 21 In the same way, he sprinkled with the blood both the tabernacle and everything used in its ceremonies. 22 In fact, the law requires that nearly everything be cleansed with blood, and without the shedding of blood there is no forgiveness.
23 It was necessary, then, for the copies of the heavenly things to be purified with these sacrifices, but the heavenly things themselves with better sacrifices than these. 24 For Christ did not enter a sanctuary made with human hands that was only a copy of the true one; he entered heaven itself, now to appear for us in God’s presence. 25 Nor did he enter heaven to offer himself again and again, the way the high priest enters the Most Holy Place every year with blood that is not his own. 26 Otherwise Christ would have had to suffer many times since the creation of the world. But he has appeared once for all at the culmination of the ages to do away with sin by the sacrifice of himself. 27 Just as people are destined to die once, and after that to face judgment, 28 so Christ was sacrificed once to take away the sins of many; and he will appear a second time, not to bear sin, but to bring salvation to those who are waiting for him.