I did the Wilderness Course until 70, then switched to the Ape Atoll course then at 85 switched to the Gnome Advanced, currently level 92.
Make sure to use the penance master horn if possible.
it wont take u long doing ape atoll and the barb advanced botting 24/7 will get you it extremely quick cant calculate it becuase i forget the xp rates and hour buts its fast.