I believe Joseph Smith, and perhaps his associates, accessed what Christians think of as the “new covenant” long before the temple ordinances were ever introduced, even as early as the First Vision. The confusion, as I understand it, is that access to that higher covenant is not through carnal commandments and ordinances, not even those within the temple on Earth.

The outward performances of the Law of Moses are done away with in the new covenant. All those kind of outward performances are fulfilled in the new covenant, and made obsolete and vanish away. The outward performances may help lead us towards the new covenant, but there are no such external performances in the new covenant itself or to come to know this covenant.

I perceive that we can’t know God, even “see” His face, through such outward symbolic ordinances and works, but many seem to believe we can, and then become disappointed and frustrated when it doesn’t happen. Those outward symbolic ordinances are just more of the same lower law in a different form. It is trying to teach us about the new covenant, and point the way, but many seem to mistake it for the actual thing in itself (the ancient Israelites likely thought the same). These ordinances are not the actual mysteries of the kingdom or the knowledge of God, no matter how good the symbolism is. God puts the new covenant and law directly into our mind and heart, directly into our consciousness, as we come to know God and the Beloved, it seems to me. (Hebrews 8; Hebrews 10)

Doctrine & Covenants section 84 talks about the two laws/covenants/priesthoods, and notes specifically that the lesser priesthood administers the “law of carnal [outward] commandments.” The true ordinances of the greater priesthood and covenant are not carnal or outward or external. They take place in the inner self, the inner soul, in the true Temple of our mind and body and Spirit, in our consciousness and focused contemplative awareness. This is where the Power (Priesthood) of Godliness is manifest, where the Fullness of His Glory is manifest, and where we enter into His Rest and Peace. This is where it is experienced. It happens inside us, not in the flesh, but in our Mind and Heart, I perceive.

I perceive that we can’t know the new covenant, unless we know God. The “covenants” that are imparted to us in the temple are more outward performances and carnal commandments. Being strictly obedient to these commandments and promises won’t bring us into His Presence either, even though they may help point the way. It is by coming to know God directly that God writes the new covenant and law directly into our mind and heart. Then we know the mind and will of God, being of one mind in God, to do it.

When we come to know Him, then we know His law and covenant very well, for it is revealed/unveiled to our mind and heart in that self-same knowing.