Hi Queen95,
Since you're not planning to apply to Business School for another 2 years, there is no reason to try to 'cram' your studies into just 3 weeks. The 700+ Score is approximately the 90th percentile, meaning that 90% of Test Takers either CAN'T or WON'T do what it takes to earn that type of Score. The type of 'cramming' that you might be thinking about rarely leads to great results on the GMAT.
In addition, while there are certain aspects to Test Day that you can really only learn by taking realistic, FULL-LENGTH CATs, once you've learned those things, it's important to remember that taking lots of CATs will NOT make you a better Test Taker. A CAT is really a 'measuring device' - when used correctly, it will give you a realistic score and help define your strengths and weaknesses, but it will NOT help you to fix any of those weaknesses. To raise your scores, you have to learn the necessary Tactics and put in the proper practice and repetitions. The CAT will show you whether your studies are helping you to improve or not. As such, you really shouldn't take more than 1 FULL CAT per week (and trying to take 'as many CATs as you can' will ultimately be just a 'waste' of practice CATs).
At this point, we have no idea what YOUR 'peak score' is, but you likely will not hit that level with just 3 weeks of study. Thus, you should consider changing your timeline to give yourself a better shot at this Score Goal.
GMAT assassins aren't born, they're made,
Rich