I think we don't know. But even if time or anything else existed before the Big Bang, we have seemingly no evidence of it, no reasonable expectation we could ever have any evidence of it, or any way to measure or deduce anything about it. It might as well not exist, for all intents and purposes it no longer does if it ever did.

By contrast, we _do_ see evidence of the Big Bang itself, and our best models today are that everything we see is evidence of (and a product of) that Big Bang.

Additionally, the space expansion aspect of the Big Bang means that space itself in some sense came from the Big Bang. Everything we see was indescribably compacted at that point and then expanded from there, over time.

So if there was anything before the Big Bang, it wasn't space as we know it and it didn't have any knowable effect on the universe we see.

In conclusion, if you have nothing, in no space, does time even mean anything?