If we focus on the moment of causing, we couldn’t get the idea of causes being in prior in time. So why is temporal priority taken as essential to causing? Because we start seeing the cause as the initiator. But even this isn’t enough – we need to see the cause as working though subordinates, so that “the effect” is either at the end of the action of subordinate causes (like ringing the bell in the carnival strong-man game) or the cumulative effect of subordinate causes making a whole (like a burning house being the sum of all its parts catching on fire).
Time is integral not to causality as such but to subordinate or secondary causes. Time is required when the primary agent is trying to act on one part after another either to reach an end or to form a whole. Do away with the secondary causes, and any temporal interval between cause an effect vanishes. Looking for it is like trying to find some time between pushing Joe and Joe being pushed.
We can consider the necessity of time not just through subordinate causes but though the substance of imperfect being. By “imperfect being” I mean one that has incompossible perfections. A person can have either the innocence of childhood, the beauty of youth, the authority of maturity or the wisdom of age, but these are incompossible, which can only be whole over an interval of time. Here again, however, we run into the subordinate causality of parts forming a whole. Time allows beings with incompossible perfections unite those perfections in a whole.
And so the domain of all time – the universe – is the totality of all incompossible perfections possessed by secondary causes.