I wanted to reply earlier, but found it hard to come up with a meaningful reply, one that could help you. Now I think I have. So hopefully you hear me out.
You say you have got a weakness with quant. Normally I would have suggested difficult problems like the ones on MGMAT and the challenges (now known as tests) on gmatclub. But then I thought, if you yourself think that you have weaknesses in certain building blocks of quant, then I think you need to work on those before you will benefit from harder problems.
So here is what I suggest, spend a weekend (say this saturday) "collecting" as many "algebraic manipulation, and number properties" problems you can find. Do not solve any for now. Go back to the sources you have been using, OG, Kaplan
(which i personally don't think is too hot), GMATPrep, PowerPrep, etc to get your list. Then categorise these into sub categories. Then i say takle these sub categories individually. Spend a couple of weeks getting these foundations right. Then do a GMATPrep, using that to highlight what you have improved on what still needs work. The last two weeks of the following month, step up a notch. Get to the harder problems. Use the forum. 3-4 days before the GMAT, do another GMATPrep, an see how you go.
I might be a good idea to do about 4-5 hours a week of verbal too, since the last thing you want is a drop in that.
Also before I finish off, I think you should use the forums as much as you can. Quant gods (such as Walker, Eschn3am, Martikus and many others) are the heartbeat of the forum and people like you and I need to leech as much knowlege off them as we can. At first when someone posts a message, I only looked at the answer and wandered off to another thread, but now I take the extra two minutes to look at how each poster solved the problem. I have found some nifty little tricks to solving some types of questions.
Do not aim to do 10000 quant questions this coming month. But make sure every question that you do (even if u get it right), you get to the bottom off.
hope that helps,
p.s (i don't think it was a good idea putting a "live" gmat question on your other thread, i'd edit that post if I were you.