Hi dsw511,
You're discussing a couple of different issues, so it will help to deal with the issues individually:
First, since you're already scoring at a pretty high level on your practice CATs, there's an argument to be made that you could study a little bit more (right now) and score at an even higher level on the Official GMAT. Since the GMAT score is good for 5 years, you could 'bank' a high score relatively soon and be done with your GMAT studies completely.
Second, Business Schools typically expect 3-5 years of solid Work Experience from applicants. While some Schools will consider accepting an applicant with little-to-no Work Experience, those exceptions are relatively rare. As such, planning to apply to an MBA Program immediately after graduating with your Undergrad Degree is probably not the best idea for you. If you know which Schools/Programs that you're interested in, then you can certainly research those Programs a bit (and even contact the Admissions Offices to ask questions), so that you can gain the necessary information and think about a long-term plan.
Third, your Quant Scaled Scores on your CATs show that you're pretty good at the 'math questions' that you face, but that you're missing out on lots of the 'strategy-based' points. The Quant section of the GMAT is NOT, strictly-speaking, a "math test." While you will certainly do lots of little calculations as you work through he Quant section, there are a variety of Tactics that you can use, patterns that you can exploit and little 'secrets' to the Quant section that will make dealing with that section a whole lot easier.
GMAT assassins aren't born, they're made,
Rich