I generally start my universe at the protostar that blew up, hit the giant molecular gas cloud, coalescing via electrostatics then gravity into balls, eventually forming us, the planet, the Sun, the solar System and likely a bit more than that.
It’s a pretty verifiable truth. It’s where we literally came from and it’s unlikely we’ll encounter ANY matter that WASN’T made by the same protostar for a long time to come.
Things get woozy beyond the protostar.
For example: I have a significant problem with Standard Candle. It’s rather absurd.