D&C 1

In His preface to a compilation of modern-day revelations or the Book of Commandments, the Lord explained -

"That mine everlasting covenant might be established;
23 That the fulness of my gospel might be proclaimed..."  (Doctrine and Covenants | Section 1:22 - 23)

This everlasting covenant is referred to on several occasions in the scriptures as "a new and everlasting covenant".  Of such, I have seen many definitions including a new covenant established in each dispensation.  For some it may seem that this is the same "old" covenant.  But the Lord explained it to be -

"...a new and an everlasting covenant, even that which was from the beginning."  (Doctrine and Covenants | Section 22:1)

It is may personal opinion that this everlasting covenant was presented and agreed to in our pre-mortal life.  Thus at that time, it was new and everlasting...a covenant of exaltation for those that comply.