Gag or kick first. If the player continues, just ban them after that. Though I'm pretty nice with those kind of stuff.. I give time-based bans instead of permanent bans.
Ask if he advertised on purpose or accident ( accidentally pressed on a bind ). If he's doing on purpose, ban him. Lenght of the ban depends on you, and how the guy is acting like. If he just joined to the server to advertise his own server, it's obviously a permanent ban.
Will the rules be updated in the !rules in the server? It is much more easy to add the new rules in that little box. So evryone can just tell them to check !rules if they dont belive on you.
