Hi Deepak,
Unfortunately I don't have the perfect answer for your question. Everyone has a different rate of learning and study habit.
BUT, there's someone who can find out the perfect exam date (100% guaranteed), this person is you! Let's have some fun with the PM tools & techniques you learned to work out your schedule.
I want you to answer to yourself the following questions:
1. What is the ideal score you wish to achieve from the mocks?
2. How much time can you allocate each day for studying?
Now that you have your goals and requirements, add up and fill the following activities in your calendar:
1. How many more mock exams are you planning on doing (I'd recommend all 8 Prepcast exams + 3-4 more from other sources)
2. How much time do you need to review each mock exam
3. + any additional time for reading
4. Leave 1-2 blank days before the exam date for relaxation & de-stress.
Hope this helps,
Joe