If I presume what you mean by the Big Bang is the typical scientific definition, then the Big Bang is creation of nothing to something. Non-material, non-existence to material existence. (And no need to argue down the rabbit holes of string theory or multi-dimensional universe theories - that’s just adding pointless layers of recursion on top of the primary point here.)
God is not defined in material terms, so there need not be anything preceeding God. It is from God which all things, whether immaterial, material, or spiritual come from. In Christian parlance: “In the beginning, God…”
Hope that helps frame for you my original argument. 🤙