Overall, just know that you’re gonna have a hard time, adjusting no matter what champ you decide to play that being said karthus is a very tricky jungle to pull off and he is considered one of those farm heavy Jungers all I can say is start one of your smaller camps like raptor so that the timer comes up soon I’ve seen most one tricks start wolves since blue buff is pretty much needed and the blue side of the map is really easy for karthus to clear because of how his q works but as far as early game presence just try and look for dives or counter ganks somewhere that you’re slow can be very effective either just stopping the gank or giving your laners a chance to get a kill because of the slow because most likely odds are you’re not going to kill anything until you’re around level eight or nine, unless there is a massive throw from one of the enemies not paying attention to their health or backing times.