Hello Vijay,
Welcome to JavaRanch. First of all, have a look at our SCJP FAQ, where you can find answers to the most frequently asked questions about the SCJP exam. You can find the link to it in my signature below.
How much time it will take you is hard to say, because it depends on your experience with programming and
Java. Obviously, if you are totally new to Java, it will take you more effort then when you already have some experience.
The K&B book covers everything you need to know for the SCJP exam. If you score well on the tests in that book, then you can be confident that you'll score well on the exam. Ofcourse there are many more resources than just the K&B book; there are also other books and you can find free or paid-for mock exams on Internet. See the SCJP FAQ for more information.
Ofcourse you're welcome to ask questions here on JavaRanch or browse through the forums here, where you'll find lots of discussions on the topics you'll need to learn for the SCJP exam.
Good luck with studying.
[ December 19, 2007: Message edited by: Jesper Young ]