Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This is how I jungle Nocturne. He is a crazy strong ganker out of the jungle, which is one of the more important roles of a jungler.
I start at blue, and have a team mate hit golem once for me and run away. This saves you about 200 damage, and speeds up your jungle, along with saving you health pots. Take your Q first because it damage golem and increases your AD. Then move to wolf, wraith, then go straight for lizard. you should be level 3 with all three skills at lvl 1. Spam q and e on him constantly, and keep health pots going continuously. Lizard CAN kill you if you go in with low health. After lizard, get golems, return for wolfs and wraiths, and you should have enough for madreds. After this you can gank freely while waiting for buffs to respawn.