My advice that I gave to quitcher was to set it to 4 bots (2v2) and have humans replace them as soon as they join the server.
The best way to populate a server (from my experience

) is to start it up and then let it wind itself down. You join the server, maybe have a few friends follow you. Try to please the new comers as best as possible, interact with them and treat them like good pals. Around the 10 player mark, you can stop caring and just leave. The server will most likely start populating itself by then.