There is one angle to the "before the BB" that hasn't been explored here yet. Extending on Darkness's excellent wrap-up of the relativity theory, there is another factor that influences the passage of time, and that's mass, or rather mass concentration.
If a lot of mass is concentrated in one place, the passage of time is slower there. The more mass in one place, the slower.
As the Big Bang started, all the mass of the universe was concentrated into one infinitely small point. This means that the mass density was infinitely large. Which has the same effect on the stuff there as travelling at light speed: no time passes for the traveller/amassed one. Therefore, at least for whatever was at the place where the Big Bang happened, no time passed and the question of what was before lacks a reference. Before and after are a matter of time, and where no time passes, before has no meaning.