0) (….Before the Beginning?)
The main problem with answering this question is that, at the moment, the only things we can truly know are events that have happened within our universe. We cannot see beyond the boundary, over the edge (if there is one) because light is not able to travel over it. If one day we could somehow ‘see’ with gravity, then maybe we might have an answer. But for now, our astronomical understanding is akin to a botanist who comes across a single, unusual tree in a field. After an intense amount of studying, he can infer what the tree would have looked like when it was younger, and can even speculate the characteristics of the seed it grew from. However, it is a whole other challenge for him to trace it back to the source, the ancient tree where that imagined seed came from.
We do, however, have some theories that help us to think about how our universe may have been born. Some describe our universe as a tiny bubble that expanded from a rupture or fluctuation in another, different universe, from some extraordinary structure like a supermassive black hole. Others say our universe is a vibrating flat sheet that is stacked, like a floating pancake, on top of other universes. When these planes wiggle close and accidentally brush against each other, the point of their meeting sparks and gives birth to a new strand, which is a new universe.
If any of these are true, then there was a point when our universe was a fluctuation, a strand, a bubble, a seed. Then once upon a time, our universe started to grow.