“I suppose you’re saying here that “time” exists independently of a timeline started with a big bang.”
Well, what I’m saying is that change can’t happen without time. If change is happening, then time is happening too. The Big Bang, as proposed, involves a change, so time must have already been in existence in order for such a change to happen.
That’s because the notion of time is wrapped up in the word “change”. I’m not that familiar with Big Bang theory, but I’m comfortable with the notion that there is a moment of time for which there is no “before”. I think the universe demands an explanation but not a cause.