Timeless cause/effect relation

I was asked a question about a timeless God's creative relation to the world.

i) It's  not so much that God exists before time but  that he exists apart from or outside of time.

ii) There's an asymmetrical relation. The world has a first moment. So on the mundane side of things, there was something new. 

But from the divine side of things, it's a timeless relation because God is timeless, so there was never time when God was not the Creator. There was no shift in God from when God was the sole existent to God and the world. No change in God. It's a one-sided change.

Here's another potential way to model the issue. Causation normally involves both an interval and a medium. A stock objection to Cartesian dualism is that there's nothing to mediate the cause/effect relation, since mind and matter are categorically distinct substances. 

However, a counter to that objection is that if effects are necessarily mediated effects, then that generates an infinite regress. 

So it seems inevitable that effects bottom out with direction causation. Nothing mediates the transaction. 

If, however, we eliminate the medium, then don't we also eliminate the interval? But if there's no medium, then it's a timeless cause/effect. There's nothing in-between the cause and effect, either substantially or temporally.