The qualifier (second part of the question) is irrelevant.
The earliest simple life that we can definitively identify as life - in the form of stromatolite fossils laid down by algae-like creatures is about 3.65 billion years old.
There is less definitive, but still robust, evidence that life is at least 3.77 billion years old -
Evidence for early life in Earth’s oldest hydrothermal vent precipitates - White Rose Research Online - and may be as old as 4.282 billion years old. These results come from fossils of microtubials, which are similar to those found laid down by extant microorganisms around modern hydrothermal vents.
Given that all the evidence points to the formation of the earth about 4.54 billion years ago, and the formation of oceans about 4.3 to 4.4 billion years ago, this suggests that life could have come into existence is as little as 100 million to 200 million years after the formation of the oceans.
With certainly, basic life - specalised microbial autolithotrophs and chemotrophs - was around within the first 800 million years of the existence of earth.
Self-replicating cells are definitely older than this. How much older - 100, 200 or 500 million years - is hard to tell.
So, in answer to your question: At the most 800 million years, but plausibly no more than 200 million years.