Hi patto,
Many Test Takers spend 3 months (or more) of consistent study time before they hit their 'peak' scores, although the amount of time that you would need to hit your score goal might be more or less than that. It's worth noting that the Quant section of the GMAT is NOT a 'math test' - it's a 'critical thinking test' that requires lots of little calculations as you work through it - so while being 'good at math' does not necessarily mean that you will automatically score at a high level in the Quant section.
Since it sounds like you're just beginning your studies, then it would be a good idea to take a FULL-LENGTH practice CAT Test; you can download 2 for free from
www.mba.com (and they come with some additional practice materials). If you want to do a little studying first, so that you can familiarize yourself with the basic content and question types, then that's okay - but you shouldn't wait too long to take that initial CAT. That score will give us a good sense of your natural strengths and weaknesses and will help provide a basis for comparison as you continue to study. A FULL CAT takes about 4 hours to complete, so make sure that you've set aside enough time to take it in one sitting. Once you have those scores, you should report back here and we can come up with a study plan.
1) When are you planning to apply to Business School?
2) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich