Jungle Path: Wolves > Blue > Wraiths > Golems > Red, Or Red > Golems based on preference.

First, A quick note before I begin this section of my guide. (About this)

Also, I take Ghost (you'd be surprised how much this helps early game ganking) and Smite as summoner spells as this is a Tanky DPS Jungle Nocturne build. I recommend even mixing up skill order to gank early, As early level ganks with Nocturne are devastating.

Start at Wolves, You should clear it quite fast with your passive combined with you're Q, Duskbringer, Then instantly progress to Blue and make sure you've asked you're teammates to help leash it for you at the least, If they will leash it for you, smite it and then look for a gank or progress to wraiths, Early ganks with Nocturne are VERY strong, Never underestimate him.
Alternate/Recovery Path:
Wraiths > Wolves > Blue > Wraiths > Red/Golems
Recovery: Wraiths > Wolves > Golems > Red, Sir ganksalot.

NOTE: You can start with Cloth Armor and 5x pots if you do not have optimal runes, although seeing as how the new jungle is so disgusting atm, it might be easily cleared even without optimal runes.
Also, If the enemy team is AD heavy, And you need a boost in damage, consider a sunfire cape, as it'll boost your normal damage output and give you a burning little aura. :)
Pro's
Great Jungler
AOE passive with lifesteal
Amazing ganker, Pre-6 Amazing, after 6 more amazing. (he can even bypass wards with his ultimate, even helping him to be even more of a sneaky beaver.)
Tanky DPS, After you get a frozen mallet, their's almost no way to escape Nocturne with an ult up, Frozen Mallet constantly slows them and your Q gives you, I believe 35% movement speed if you've hit them with it. You can use your ultimate to chase them after they flash, improving its usefulness. You basically have a 65% movement speed difference between you and your assaulted enemy.
Fear? 2 seconds? With your damage? *Beautiful*
A spell shield, That makes it so that you KILL FASTER if they use an ability on you when you have it, Makes them wonder if they should use the ability or save it for when the shield comes off.
Good in solo queue especially, and when using ultimate in team-fights amazing in 5v5 premades. Tip: Use your ultimate to give you're AD carry a boost in concealment/safety, It really helps if the enemy can't see you're AD carry for a few seconds.

Con's
People get scared when they see a Nocturne ult and sometimes end up running into a bush, not allowing you to dash to them :(
Somewhat mana hungry
This build is more for supporting an AD carry, to deal nice damage and take it as well.
Not much else to say that I can think of right now, Nocturne's just a really solid tanky DPS champion.