Jax's true potential is unlocked if he gets fed in the beginning. on a 5 or 3 map i usually take solo lane, this is much easier to get kills with. On a 3 map it is okay if you go for the beginning gank, but make sure that you recall at 1:20 because it is important for Jax to get his levels. As soon as you get lv 2 you can go for your first kill. If you are a little more Cautious you can wait 'till lv 3 where you have empower. Normally you would need an auto attacker to activate your stun, but this is what I do; As soon as i reach lv 2 I wait for the next wave of minions to come by, the more minions the more people attacking you which increases your chance of stunning them if they try to run away. then throw an Exhaust after the stun and generally you keep whacking at them until they die. fast kill, nice and easy-ish, hopefully. If your lane opponent leaves, just send a mia and keep on leveling untill lv 6 where massive ganking time begins. This guide is short because it all focuses on being fed early game.