Radhika,
I used 4 months to prepare while working full time.
Month 1 - 35 Contact hours - PM PrepCast, PMBOK - Tried to understand PMI mind map (Process groups vs Knowledge area table) for the certification
Month 2 - Got a thorough understanding of the of 47 processes and how they interact, some ITTOs.
Month 3 - I got audited and things slowed down a little bit (worked on my audit package)

, more ITTOs.
Month 4 - 17 full-length simulated exams of 200 questions each, random practice tests online.
Hope this helps.