Since the planet is only 4.55 BY old, that might be considered a fast start. Some people have found some rocks (3.7 BYA) in Greenland with what they think are indications of life (short article, a bit longer article). The indicators are primarily microscopic hematite tubes (some say, similar to tubes of biological origin found in more modern vents). This is of course controversial. Hematite is an oxidized form of iron (Fe2O3). The atmosphere at that time had little or no oxygen. They hypothesize that there were microbes living at the equivalent of mid-ocean vents, where hot water extracts minerals from the rocks that could provide an initial energy source for the first life forms (generally a popular explanation now for the first life forms). I'm not clear on how the hematite becomes oxidized in these conditions. Due to actions of the living bacteria (or whatever), or from a fossilization process after they die? Is the oxygen coming from the dissolved minerals from the vents?