When were God's promises concerning the seed set, relative to Adam's creation?
God's promises concerning the seed were set in eternity past, before Adam was ever created. The promises go all the way back to eternity past, before Adam was created, and all these things were already set in God's plan. They were established before Adam's creation, not after.
Les explains that these promises go all the way back to eternity past, before Adam was ever created. He emphasizes that all these things were already set in God's concrete, using that term to describe their fixed certainty. This connects to the promise that at the set time God would come and Sarah would have a son, Isaac, through whom the singular seed, Christ, would come. The seed of the woman could not come through Ishmael or Esau; it had to come through Isaac. So the seed promises were settled in eternity past, before Adam's creation.