Colossus Boulevard will prepare you for facing multiple foes in a duel. If you begin in Krokotopia and feel that you're not quite strong enough, you can always fall back to Colossus Blvd. to gain a little more experience (and confidence in your character) before you adventure further.
I am a level 12 Diviner (storm wizard) and ready to move onto Krokotopia. Do you think it's wise to complete Colossus Boulevard before starting Krokotopia?
I do about 1/2 this instance. I do it up to and including talking to the Gobbler King. After that, I'm out. I've gained more experience, etc., as suggested by Prof. Greyrose, but haven't wasted a huge amount of time. :)