Hi Zbigi,

I started working with Oracle feb 2000 (previous little experience in IT).

Started OCP for DBA in may and ended in november and took 4 weeks for a holllyday.
On average I prepared for 4 weeks per Exam having a full time job, a wife and two kids.

For preparation I used Couchman and Oracle online documentation (all) and Exam Cram (last three).

I bought one STS and there were at most 5 duplicate questions.
STS tells you which subjects to study more intesive.

HTH

tycho