This'll be short and simple. No fancy ****. I'll just be giving short overviews of what Jungle Blitzcrank does in each section.

Read the Build Order section's notes. Those have most of what you need to know, and if you really insist on variation, then you yourself should know how and what to build.

(On that note, building Blitzcrank exactly like Jax is amusing.)

Start wolves->blue. You want help on wolves and a leash on blue; Blitzcrank's first clear leaves him low and without his passive shield otherwise. Move on to wraiths, then back to wolves, and then red. At this point, you may make your first gank, which is entirely inescapable.
Ganking process:
Come from behind or relatively the same spot, horizontally speaking. Hit W (you can't be kited with the build I posted at this point - not even by Ashe), hit E, autoattack them once to knock 'em up, and keep going at 'em with your allies hounding them too. If they get too far away while running or get behind their turret, use Q to grab them back (but stop chasing if they're within turret range so you grab them away from turret range). If your E refreshes at any point during the gank, use it again.

AD Jungle Blitzcrank has the strongest (early) ganks (on average) I know of. Other junglers are much easier to escape and do less damage without items. Blitzcrank's base stats and early game strength on his abilities are good enough to even counterjungle and trade with nearly any other jungler. It's also really, really easy to steal their buffs with a pull.

Note that your clears will suck at first. This is normal. Just get fed as hell ganking, and once you hit 6 your clears will go by much faster.

If the enemy team made it this far without surrendering, kudos to them! At this point, what you want to do is punish the enemy HARD for going out of position or overextending. You should ward as much as possible so you can surprise grab the enemy should they wander into the jungle. Team ambushes are great.

Basically, not that different from Support Crank, except you actually do damage. Chasing powers are great, aren't they?

tl;dr don't be that idiot who pulls the enemy into the river/forest and away from the laner in order to gank. It doesn't work during laning phase.