well, if you prescribe to the open universe model, where a big bang, which results in expansion, followed by contrattion into a Big Crunch followed by another Big Bang, ad infinitum. then what was before, or after is all much of a muchness. as they say in battlestar galactica, 'all this has happened before'
whereas with the closed model. big bang from nothing followed forever more by expansion, then nothing will exist yet again when everththing has expande d so far away from everything else as to have no effect. excep that gravitational force is exerted with no time delay. (oops, brain addled by old age can no longer remember what was crystal clear as a geeky teen)