Hi st19931219,
A 630 is a strong initial CAT score (the average score on the Official GMAT hovers around 550 most years). That having been said, there are a variety of different factors that can impact your performance on a Test - and if this is your only CAT result so far, then it's not clear how detailed you were about taking this CAT in a realistic way and whether you may have gotten a bit lucky or unlucky with this performance. 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.
Many GMATers spend 3 months (or more) of consistent study time before they hit their 'peak' scores; from what you describe, your overall planned study timeframe is closer to just 2 months though - so with that shorter study window, there might be a limit to how high you will be able to Score on the Official GMAT.
Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on how you've been studying and your goals:
1) How many hours do you typically study each week?
2) Have you used any other study materials besides the books that you mentioned?
3) Are you planning to take the At-home GMAT or are you planning to take your GMAT at a Test Facility?
4) When are you planning to apply to Business School and what Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich