If you're going for a 750, then you really can't set yourself a hard deadline for the test date. That's SUCH a high score that you're going to have to assume that you'll just take whatever time you need to take. Progress isn't typically linear on these kinds of things and that's especially true at very high scoring levels.
(Over the years, I have spoken with many people who are trying to score 760+ in order to teach with us - which is really the only reason why anyone would absolutely need a score that high. :) Most of these people are already in the 720 to 750 range - real test scores. And many of these people have taken 3+ months, sometimes 6 months, just to get that last 10 to 40 points - and some people never make it.)
Read this:http://www.manhattangmat.com/articles/7 ... erence.cfm
Next, it's good that you've identified time management as a major roadblock for you. Read this:http://www.manhattangmat.com/blog/index ... to-win-it/
And then read this and start doing what it says:http://www.manhattangmat.com/blog/index ... anagement/
It typically takes a good 4 to 6 weeks to fix significant timing problems. I'm telling you this so that you can think about how you're going to decide what to do if it turns out that you need more time than you have currently given yourself. Is it more important to take the test when scheduled (maybe because you have a deadline)? If so, you may have to decide to be content with a lower goal score. Or is it more important to get the score, in which case you may have to decide to postpone the test?
You don't have to decide that now, but you should think about what's important to you so that you can make a good decision if it comes down to that.