“A poorly phrased question, since time is postulated to be a consequence of the big bang. There is no “before”.”
If time didn’t start until after the big bang, then the big bang could never have happened. Without time, no change could occur, so whatever pre-existed the big bang would just continue to exist unchanged.
But...that happened in THIS universe, what about the multi-universes?
“Without time, no change could occur, so whatever pre-existed the big bang would just continue to exist unchanged.”
Well, there could be a “timeline” outside of ours, from which we are a consequence. As an analogy, an author has his own timeline, independent of the one in a book that he wrote. He’s free to read it from the beginning, middle or end as he chooses.