This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
I don't think there's a hard and fast rule about how much experience you ought to have before sitting for the exam. IIRC, I think Sun doesn't have any specific recommendation for how long you should have been working with OOAD and Java EE 5.... but I think that definitely, you should have some practical experience designing software before you sit for the test.
Theodore Jonathan Casser
SCJP/SCSNI/SCBCD/SCWCD/SCDJWS/SCMAD/SCEA/MCTS/MCPD... and so many more letters than you can shake a stick at!