Asking such questions here may confuse you even more than you currently are. some of us may say that postpone the test and some may say otherwise. And there is a chance that you get carried away with someone's post which manages to impress you the most. So, my suggestion is do what you feel is best for you. And yes, what I feel about your situation is jotted down below.
Generally, a minimum of 4 months time is required for a 'decent level' of preparation that will fetch you a good score (again IMO a good score is 720 and above).
No matter how good/bad you are at each of the sections, you need to have as many questions as you can, solved and understood properly. You will get questions wrong, everyone gets them. The key is - practice. understand every question you got wrong and try to increase the number of questions you attempt each day.
Nobody knows how the Quant/Verbal section is split up on the test. The people who have crafted the test are gods. Let's not try to think ahead of them. I would treat each section (and each part of a particular section) as equally spilt up and prepare accordingly.
Now, should you postpone it or not? if you feel that the preparation is not enough then it's not fair to say that you want to gain the experience of the test worth $250. There is no dearth of mock tests available on internet and these tests are equally good as the real one. Take a month or 2 more, prepare what you feel you are not good (good enough) at and then take a shot.
Yes, the schools look at all of your scores (ofcourse the 5 year rule applies) unless you score a 600 on the first test and a 780 on the second. So why not postpone it and try to score a 720 on the first one and never take another.
The books -
1. all the OGs - 10/11/12
2. choose any prep vendor (one at a time please), be it Kap, Man, or Pri, everyone of them is equally good. You finish all the questions from one and you can move on to second.
3. Take mock tests as many as you can
4. the most important - Make sure you understand why you got a particular question wrong. This will help you create a strong foundation of your concepts.
There is a quote i read somewhere - 'I didnt fail 1000 times, I just found 1000 way that don't work'
It applies to the practice questions, but DOES NOT APPLY to the real test. People dont do well on real test mainly for one reason - Lack of practice. All the other reasons are actually children of this one.
I have messed up my GMAT 3 times in 2008. My fourth attempt is...well, see my signature
Hope that helps, sorry if i was rude somewhere, i didnt mean to be !
********It's June 23, 2012********