Hi CovenantInBlood
you wrote
Further proof that this covenant is already in effect

"For this is My blood of the covenant, which is poured out for many for forgiveness of sins" (Matt. 26:28).

"This is My blood of the covenant, which is poured out for many" (Mark 14:24).

"This cup which is poured out for you is the new covenant in My blood" (Luke 22:20).

"This cup is the new covenant in My blood" (I Cor. 11:25).

All those scriptures pertain to the CovenantInBlood which was fulfilled in Christ at His 1st coming and were written in the law of Moses as a shadow.

Theres no mention of blood in Hebrews 8.