If you’re looking to get that fourth “Elite,” pretty soon might be your best chance. Arena is famously extremely dead, but I suspect that the release of Odyssey will bring it a brief revival.
Obviously the release of any new DLC brings with it an influx of new players, as well as old players who put down the game and are returning to try out new features. When Horizons came out, I did notice a slight uptick in Arena activity. But Odyssey is a little different. Horizons was extremely focused on exploration features, and generally appealed to long-term Elite fans and fans of hard sci fi and sim games. Odyssey, on the other hand, has a ton of RPG and Combat features that will have a much broader appeal and will directly appeal to audiences that like match-making based action games. I strongly suspect that the release of Odyssey will bring a large number of players who will be interested in playing the Arena.