Hi Samloke,
Just speaking from my own experience, I wish I could have taken about 3 months to prepare. I decided to apply to MBA programs in December 2002 and most of the applications were due in February 2003 to be qualified for scholarships. As a result I rushed, studied for about 3-4 weeks, and did poorly the first time I took the GMAT. My big issue was timing. The timing for the GMAT CAT takes some time getting used to so I would suggest taking a day or two to get used to the format of the test, then a week or two of math review (if you can't remember some stuff) as well as verbal/grammar review. During week 3 or 4 I would suggest working through some review books (I recommend using the book ETS put out "The Official Guide" for GMAT Review). This will give you an idea of what the real test questions will be like. A supplemental review book, such as "Cracking the GMAT" by The Princeton Review, will provide you with some useful test taking strategies. Then during the last month of review I would work on practice test and definitely get the timing down. When you practice, make sure to spend only the time you will spend on the "real" GMAT on each question. This will help you prepare for the actual test and maybe you will feel a lot less pressure if you have your timing down. It's all about timing and completing each section. The second time I took the GMAT I actually finished the entire test (as opposed to the first time when I finished about half the questions in each section) and as a result my score was considerably higher.
Good luck and hope that helps a bit.