NASA will whittle the competition down to 52 semi finalists per group, each representing their state or territory. The public will have a chance to vote on nine finalists in January 2020, and you'll find out the name on February 18th, 2020, a year before the rover is expected to land on the Martian surface. There's a long way to go before the bot has an honest-to-goodness name, then, but you'll have an idea of who's in contention months beforehand.