Leese7, a 150-point improvement is possible, but it's not an easy thing to achieve. It's possible that your weaknesses can be fixed in 35 days, but it depends on what, exactly, is holding you back--there really aren't all that many people who have achieved a 150-point jump in roughly a month, though it does happen. Sentence correction is arguably the most "improvable" part of the test in a short period of time, so it's actually encouraging to hear that that's your worst section... but to gain 150 points, you'll probably need to improve on virtually every question type.
Is there a good reason why you're in such a hurry to take the test? It can be very difficult to make such a massive improvement when you're under such a time crunch, since you won't really have time to go into GMAT topics in much depth--generally, 35-day "crash courses" require that you cut a few corners, unless you're able to study all day, every day... and even then, you risk burnout. In an ideal world, it's wise to prepare as intensely as you can, and sign up to take the test only when your practice test results are close to your target score. Again, your target score might be achievable in 35 days, but I would recommend a more flexible approach if your schedule allows.
You mentioned that you've hired a tutor, and it should be his/her job to monitor your progress and ensure that your test date and study plan actually make sense. Make sure that your tutor gives you concrete feedback on your progress, and make sure that you leave each tutoring sessions with a concrete study plan. If your tutor is giving you a plan, follow it—he or she probably knows your individual GMAT brain far better than any of us here on the forums.
Good luck with everything!
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