I'm a lvl 6 Ivern player and this is this is the build i use, which gives me loads of ap and attack speed very usefull in solo fights or in team fights.
The way I normally go about jungling is I get my q first and start at blue and end at krugs in this sequence:

Blue (smite)

Gromp (no smite)

Wolves (no smite)

Raptors (no smite)

Red (no smite)

Krugs (smite)

once I smite krugs, i'll move backwards to collect all these camps that have had my passive working on them. by the end of this I should be half way to level 5. I would then either gank mid or top (and if possible get crab with me. I wouldn't be able to smite it though since smite wouldn't be up yet.)

Anyway. I hope this build helps anyone out!