How did it all begin? There are only 2 ways to explain how existence began.
(1) There was nothing and then at some point nothing turned into something.
(2) Existence never began because it has always existed.
Explanation (1) violates a basic axiom. It violates the law of identity. How? Nothing doesn't do anything. It is nothing! Explanation (1) assumes that nothing can turn into something. Therefore nothing can equal something. It means that "A" equals "not A". Therefore explanation (1) is unintelligible. We cannot make any sense of it. If it were somehow the case that something could come out of nothing, then knowledge and reason would be impossible. Why? because it would undermine the foundation of knowledge. The theory of the Big Bang (according to Stephen Hawkings) and the idea that God creating existence Ex Nihilo assume explanation (1).
I believe in explanation (2) because it does not violate the basic axioms. If the Big Bang theory is correct, it must be the case that the Big Bang is only the beginning of the universe in its current organization. The basic constituents of reality must have always existed.
Therefore the question "When did it all begin?" is a meaningless question because there is no "beginning of it all" to refer to.