Actually, I have not downloaded and read the JSP & servlet specs, I just have an idea of the specs from the lines written on the first page on each chapter in HSFJ.
For the preparation time, actually, I intended to take the SCWCD 1.3 exam more than 18 months ago. I had finished the reading on Jan 2004 but I found that SCWCD 1.4 would be released soon. So I postponed to take the exam and waiting for HSFJ to be published. However, the publish date of HSFJ had been delayed from June 2004 to Sept 2004 and I have some personal issues to deal with at the second half of 2004. Then I restart my study again in Mar 2005, but I do not spend to much time to study everyday. When I have spare time, I will spend less than 2.5 hours to finish reading and complete the quiz for each chapter. After reading HSFJ thoroughly twice, and spend one week's time to do various mock exams, I pass the exam with ease.
To sum up, I think if you can spend about 6 weeks' time to study HSFJ intensively. And finish most of the mock exams listed in the thread I mentioned earlier (on average I got more than 80% for each mock exams), then you can pass SCWCD with high score.