Hey guys. Giest here.
This is my very first mobafire build, I've been a constant user of builds featured on this site for the last couple months. I have only just decided to create my very first build to share my thoughts on Jungling as Jarvan.

There are many different thoughts on this new champion. Personally, I think his skills are dreadful for laning with, others will disagree. I also think he makes a terrible tank, and a terrible pure AD DPS. (I would assume AP DPS would be just as terrible, but I'm not going to say anything since I haven't personally tried it.)

My job here is to explain my choices, and how I play Jarvan, your job is to give me some feedback and let me know how this build works for you.

Pros-
Quick jungler
Ganks before level 4 if you see an opening without much risk
Gives an ally a solo lane top (Allows a team mate who can manage 2v1 or 1v1 to level faster)
Extremely fun to play
If you initiate a gank properly, there's no escape without a flash

Cons-
Reliant on blue buff all game
If you initiate a gank improperly, you probably just killed yourself.
People who think he's better in a lane will get mad at you jungling.
Low magic resistance till Merc Treads/Hexdrinker

Jarvan is an extremely versatile jungler. There's many different runes you could take.
This is the personal rune set I've had the most success with.

Attack speed reds = Attack speed is always nice, Armor Pen would also work for this slot
Armor Yellows = The early armor lets you jungle longer and gank AD users without much risk. Attack speed or Mana Regen would also work.
Cooldown Reduction/Level Blues = A personal favorite, with these and blue buff you'll have your ult about every 55 seconds at level 18. Attack Speed, Magic Resistance, or Flat Cooldown Reduction could also fit in nicely.

I'm sure a lot of you won't be enjoying the fact that I went 20 / 0 / 10. It seems rather unusual right?
I assure you, you won't even notice that you're missing the 5% damage bonus from attack. But you'll definetely notice the 15% more buff duration.

There's not a lot else to explain, smite mastery because Jarvan doesn't need Exhaust or AP.
No magic pen, because it would only affect your Flag, which does a fair bit, but not enough to need 15% pen.
Ignoring the critical strike because we're more focused on auto attacks and moves, not very crit reliant.
And ignoring the 5% damage bonus for the reason mentioned above.

In the utility tree, HP/MP regen is nice, the EXP increase is a must, and the buff duration helps to solve the mana issues on Jarvan.

Smite = you're jungling, I would never jungle with someone without smite. You'd be at a disadvantage to any enemy jungler with it, they could steal your dragon/baron/buffs. And having smite speeds up your first couple trips through the jungle.

Ignite = This one is optional. I've had much more success with Ignite then I have with Ghost or Flash, but if you'd rather have a speedy Jarvan, or a Jarvan who can use his ult to save allies without being at a risk himself, take Ghost or Flash as you wish.
If you do take Ghost, take a point out of reduced Death time in the utility tree and move it into increased Ghost duration.

There's many different ways to skill for your Jarvan. And it depends a lot on your playstyle.

I think almost everyone will agree that you should focus on maxing his E first, the passive attack speed and armor, along with the use really make it an excellent first choice.

I take 1 point in his W at level 4 just to reduce jungle damage, as well as having the shield and slow for ganking.

1 Point in Q at level 2, to help jungling and allow you to gank immediately if you see that you could go gank a lane already.

Obviously maxing his Ultimate is priority, it's amazing. Just be careful about the placement of it, you don't want to trap allies inside when they were trying to run away at 100 health.

Here's my last 10 matches. Of the 10, none of them were a full 5 man premade. 6 of them were pure randoms. 1 of them had me and 2 friends. And my last 3 wins were with 1 other friend.
(On a personal level, this is amazing to me, because it's the first time I've ever managed 10 wins in a row on a single champion.)
2 of them overlap, sorry if you don't like it. But at least it shows these were done all in a row and they're not just mixed and matched.

Start with a cloth armor and 5 health potions, just like most junglers.

The jungle route that I use is not the fastest, but it syncs very well with timing ganks.
I start at the enemy teams' wraiths. Be careful because some enemy junglers will notice you, but most of the time you should have no issues with this. Smite the blue wraith, kill 2 of the red ones, and leave 1 red wraith alive so that they don't respawn anytime soon for the enemies.

Next stop is your teams' wolves. Pop your first health potion as you get close.
You should hit level 2 at this point head towards your wraiths

As you near your wraiths, pop another health potion, Toss your flag so that it hits all 4 of the wraiths, use Dragon Strike to pull yourself in and knock them all in the air, and ignite the blue wraith (This is really up to you, I prefer it because then it won't be lifestealing as much, and you can kill it 2 hits faster)

After wraiths you should be level 3, pop your third health potion and head towards small golems. Smite should be back up at this point, start hitting 1 golem, smite him, then kill the other one.

If you followed this exactly and moved as fast as you can, you should have 400 gold. Start to base, you should base with 410 gold, wait 5 more and buy a long sword.

Head towards blue buff now, the goal is to take blue buff with smite just as it comes off cooldown. The timing should be that when smite comes off cooldown, blue buff has about 400 health left.

After blue buff you should be level 4, get a point in your shield and head towards red buff. Take red buff by spamming all your skill as much as you wish.

Time to base again, buy your Madreds Razor, grab 2 health potions and a mana potion
With both buffs, your shield, and your razors you're ready to gank.

The rest of the items are situational and replaceable. I strongly recommend using these items I've listed, but if you see that none of the enemies are AP, maybe get a Randuins instead of a banshees. Feel free to change it up based on the enemy team.

Before level 6, the earliest you can gank is level 2. If you try a gank at level 2, be sure your allies will help, you don't want to give up a free kill probably worth first blood by being too greedy.

The first thing you want to check is which enemies have Flash, if they have Flash, don't expect a kill with or without your ult the first time you gank. The goal of your first gank is to either
A) help an ally who needs you to cover their lane
B) Get a kill
C) Burn an enemies Flash for a later gank

Your ganks will always be E>Q>W>R
You don't want to throw your ult immediately. I see way too many Jarvans using their ult at stupid times. Do as much damage as you can before resorting to your ult.
If they're starting to run, pop your ult on them to lock them down, use the combo above again, but don't pop your W until the wall from your ult are just starting to dissapear. when the walls are dissapearing, get your slow on them, ignite them, and try to land another flag on their head.

I'm still working on this guide. But it's finished enough to be published.
I plan on adding in pictures instead of text to make the guide section look much more pretty. But I wanted to get this guide out there for all of those Jarvans who want to try Jungling.
I'll also be posting pictures of my match history, within the next couple days.

Have fun guys
-Giest