We also don't have timescales for abiogenesis in a sterile environment - i.e. given the right ingredients and energy input, no existing life forms...how long does life take to appear? There's no particular reason that timescale has to be very long - and we know life on earth got started pretty damn quick after the planet cooled off enough (EDIT: in the sense that the planet is ~4 billion years old, the earliest life is dated to 3.5 billion years old, so the number is somewhere between a little over 0 and 500 million years).