Just played Shaco yesterday. First of all, Golem buff > lizard buff at level 1. You need the mana to spam shiv and jitb.
Secondly, the proper way to jitb Golem:
1) At the start as soon as the game comes up, grab your items as fast as possible (I go meki's to regen on jitb CD and also 2x health pots).
2) proceed as fast as you can to the Golem. You want to arrive at or before the announcer saying "Welcome to Summoner's Rift".
3) While you are running to Golem, select jitb as your first skill.
4) When you arrive, stand in the nearby brush and lay your first jitb down a good distance from the Golem and minions so it doesn't trigger right when they spawn. You really need to get it down asap when you arrive at Golem to start the CD.
5) Be timely with your cooldown so you can lay the next jitb at a similar distance as the first one.
6) You should be able to drop 4-5 jitb by the time "Minions have spawned" sounds.
7) When Golem spawns, walk behind him so you get the 25% passive. When you hit him, walk him back towards your pile of jitb. He will get feared.
8) At this point, he should be focusing on the jitb's while the minions might be hitting you. Position yourself behind golem for your passive to work and finish him off as your last jitb dies.
9) Your jitb will actually be off cooldown right as the golem dies. Feel free to drop another one to help finish off the minions.
10) Remember to use your health pot early (around 80% hp) so you don't leave with extremely low health -- the whole point of getting the golem buff is so you can begin strong harassment with shiv and jitb and hope for an early kill. However, if you leave with low hp, it's likely you'll be killed first anyway.