Hi aadirenpronk,
Since you've given yourself plenty of time to study, you can certain begin this process however you choose - and you can make adjustments later as needed. I do have a few suggestions though:
1) In your original post, it sounds like you've considered the possibility that you'll take the GMAT 5 times. While there's always the opportunity to take the GMAT repeatedly, that should NOT be the plan.
2) Most of the materials that you've listed are books. Many Test Takers who use a 'book heavy' study approach tend to get 'stuck' at a particular score level. While that may or may not happen to you, you should consider investing in some non-book resources that will help you to practice in the same 'format' that you'll face when you take the Official GMAT.
3) For free math practice and help, I recommend that you set up an account at Khan Academy (
www.khanacademy.org). The site is completely free and makes the learning a bit more fun and 'game-like' (as opposed to the dry academic approach taken by most books). While the site is vast, you should limit your studies to basic Arithmetic, Algebra and Geometry.
I also suggest that you plan on taking your next FULL-LENGTH CAT in about a month and post back here with your scores. With that score result, we'll have a better idea of how you study plan is working. If you have any additional questions, then you can feel free to contact me directly.
GMAT assassins aren't born, they're made,
Rich