Oracle recently released the much anticipated SampleApp virtual box (version 511) which comes packed with OBIEE 12c and all of its great new features.
You can download it here.
SampleApp usage has always been a great way to get first hand experience of OBIEE. You can gain hands on experience before you're ready to unleash it to your clients.
I'm an Oracle Ace Associate and a certified OBIEE 11g implementation specialist.