When Hebrews says the first covenant was dedicated with blood, it tells us what it's talking about:
For when every commandment of the law had been declared by Moses to all the people, he took the blood of calves and goats, with water and scarlet wool and hyssop, and sprinkled both the book itself and all the people, 20 saying, “This is the blood of the covenant that God commanded for you.”
So to say it happened at Adam and Eve is to ignore what's written in the text.
Like I said before, there are sub covenants within the Old Covenant. The Bible does say that he took away the first that he may establish the second (Hebrews 10:9). Testament means Covenant, and the Bible is divided up into two testaments or covenants.