Hi Aseem,
I suggest to read some good java books (head first is the best one), do some
test coding, do as much as mock exam as posible.
For time frame, its depend on how much time you spend for study.
I took about 2 months partime preparation (1-2 hours/workday).
Practise the mock exams, if you score around 80% then you are ready.
Good luck,
-Ricky [SCJP, SCWCD]
Java Certification Voucher for $150 [ September 10, 2007: Message edited by: Ricky Ignatius ]