Hi Paddyphone,
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.
You've already defined your goal score and the approximate date that you'd like to take the GMAT - which is good. I have a couple of questions about your overall goals:
1) When are you planning to apply to Business School?
2) What Schools are you planning to apply to?
There's a significant problem for many Test Takers who use a "book heavy" study approach. Even the best books are limited in what they can teach you; they also can't force you to approach questions in a certain way and their explanations are often one-sided. Considering your goal score is essentially the 90th percentile (meaning that 90% of Test Takers can't score that high no matter how many times they take the Official GMAT), you might want to consider other study materials besides books.
GMAT assassins aren't born, they're made,
Rich