What assumptions? What I say follows straightforwardly from the meanings of the words I used. There can’t be a “before” time itself, in the same way there can’t be a further north of the northernmost point.
As far as I can tell there had to be an initial event according to BGV, and the cause and effect of that initial event could have happened spontaneously.
I don’t see how this relates to what I wrote. The BGV theorem does not imply a transition from a state of absolute philosophical non-being to a state of the universe existing. Rather it merely implies there was a first moment of time in the sense that the length of the dimension of time into the past is finite, it has an “end” in the past. The theorem doesn’t say that there was “nothingness” somehow even further before this first moment of time.