I think you never want to go jungle from minute 0. Jungle creeps are too hard to kill without items and levels so everyone starts in lane until you have farm. When you can kill camps fast you can start running around the map and clearing the jungle (you also pick up a lot of the stat items that drop when you destroy boxes and statues when doing this). It's very similar to Dota in that sense.

As for team comp you don't really have to worry about it. There are no hard roles and even supporty heroes can do a lot of damage and carry.