Is this a good studying plan to follow?

I think I'll be combining yours with some other plans... thanks a lot for providing such great resources.

I thought I'd start out tomorrow, which is the 2nd of October, by taking the first GMATPrep test. If I've understood it correctly, I can take two of those? Will doing the OG questions first ruin the GMATPrep tests? I heard they were based on the same questions.

My test appointment is on the 23rd of October, so I have about 20 days to prep. However, I think I'll be able to put my studies a bit on hold and put in 5-10 hours a day.

Edit: By the way, I have these books: Kaplan 2009, Offical Guide, Official Guide Verbal & Quant, and the Manhattan Verbal & Quant study guides and solutions.

Jules,
I actually combined Eric's plan with the shaved down version of the 300 hour plan that was on that site. My background and reasoning was a bit different, so I saw the need for more time spent on studying. While I have deviated a bit from my plan, the crux of it can be found on my blog here:
https://mbabrian.blocked/

Hi Jules,
I think Eric's plan is great. It's good to have a gameplan to stay focused. Make sure you take a test prior to studying. Then a test through about half way. This will help you track your progress. I am trying to put a clear gameplan on my blog here: https://800gmatblog.zoxic.com/

I shouldn't worry about "wasting" a GMAT PREP test at the beginning of my plan?

Personally, if you think you still have fundamental math or verbal skills to hone up, I wouldn't take it until you've had a chance to freshen those trouble areas up. You could substitute a MGMAT or Kaplan in there for the beginning and then take the first GMAC test after a couple of weeks of brushing up. Unless you're confident you have a good fundamental base, then go ahead and take it. It's kind of a bummer that you only get two of the tests from GMAC unfortunately.

I was really unsure of my level so I took the GMATPrep to see.

So, before any prep whatsoever I got a 630, Q37, V39. Sort of messed up because I didn't pay attention to the clock at the end of the quant section, and time was up with six questions still unanswered.

I think I should have prepared myself a little better because I was caught very much off guard by the quant. In addition, English isn't my first language so I've never had any maths in English, which meant I had to guess what some words meant, like integer. I need to improve my quant skills anyway. Verbal was better but I haven't had time to look at my answers closely.

My minimum score goal is 650, I guess I'm not too far off. How accurate are these tests?

Time to set up that plan and get to it then....

And thank you all for your help, by the way