" - there are no experiences at all. "
Except the experience of no experience...experiencing being aware of being aware which requires no sensory input or even a physical body with a brain, that is when the true present moment occurs since it has always been and always will be...there is no time with awareness being aware that it is aware.
Asking the question "What happened before the Big Bang" is legitimate in the context that it is questioning the assumption of a Big Bang to begin with. If we say there is nothing outside the configuration space we have just proclaimed there is something called space; meaning there is an object with a boundary. We cannot have a boundary without something outside that boundary since that what defines the boundary to begin with. If we say there is no boundary to space then there is no expansion of space to begin with since it has no boundary and has always been spatially infinite. If we say there is a timeless mathematical object with time existing within it then we have just contradicted ourselves by saying it has no time yet it has it itself. By calling it a timeless mathematical object we are saying it doesn't exist except in our concept of it and since we are conceiving of it now it does exist since how could it not if we are able to conceive of it, and that conception has not changed over billions of years and since no change equals no time it is eternal. And if there is no t outside of it then there can be not expansion of it since it has no boundary, hence any notion of the Big Bang being an expansion of time and space remains such as that, a notion - without real physical reality; There was no beginning of say 14 billion, 18 billion years ago...it has always been and always will be.