The most fundamental property of reality is logic, the most basic elements of that being Truth or Falsehood.
It makes up the essence of computers (0 or 1s), but also our reality, the universe.
No matter how many dimensions or universes you think there are, logic is the basis of it.
From logic, mathematics is birthed. From that, physics is possible. From that, chemistry and physical complexity (arguably a subset of physics anyway). From that, biology (more complexity). From that, consciousness. From that, #Bitcoin ... LOL I had to say it.
Anyway, without logic, there is no reality, and we can answer the original question like this...
If there "was" a time (better to say a "state" to not assume time existing) when nothing existed - truly nothing, then it would be TRUE that nothing existed. But truth is something, not nothing.
This means that nothing cannot exist in our reality.
For nothing to exist, we have to step outside our reality. In this domain, there is no logic. In such a state where truth can equal falsehood, or a man can have periods, anything is possible. Also, EVERYTHING is possible; Also, neither of those things are simultaneously not possible on Tuesdays. It's completely illogical and not real, not reality. Much like Jeremy Bearimy (watch The Good Place for the reference).
From this Jeremy Bearimy state, where anything and everything is possible and impossible, what can come to existance? A pocket of Logic (Like how Douglas Adams' impossibility drive was created from the improbability drive and a good cup of hot tea)
In this logic pocket, things make sense, and reality begins, with whatever starting properties Jeremey Bearimy birthed.
For the religious people, I don't know how to fit God into this exactly... Maybe God is the idea of Truth, and His counterpart, the idea of falsehood?
And maybe this answers the question, "If God created us, who created God then, smart arse?" - Maybe the answer is "Jeremy Bearimy did", or maybe, God is Jeremy Bearimy?
