A 230-point increase in 21 days is rare. I typically suggest that students achieve their target score on at least 2 practices tests before they take the official test. So, if you get to the point where you're 1 week from test day and you haven't reached your target score, you should probably reschedule.
A quant score of 39 is in the 46th percentile (see
https://www.mba.com/the-gmat/gmat-scores ... means.aspx), so I think that you have quite a big of work to do there to reach a score of 50 (89th percentile). Likewise, a verbal score of 17 is in the 18th percentile, while your target verbal score of 34 is in the 70th percentile.
I say all of this because, at first glance it seems that an increase from 39 to 50 seems pretty straightforward/realistic in a 21-day period, as does an increase from 17 to 34. However, you're basically hoping to advance your total score from the 25th percentile to the 89th percentile. This is a pretty tall order especially given the fact that you want to accomplish this is in 21 days.
Okay, that's all I want to say about that.
If it's the case that you have no choice but to write the test on Sept 5, then I suggest that you first focus on concepts that have the greatest return on investment (ROI). These are concepts that are tested frequently and require the least amount of time to learn. In my opinion, these concepts are:
- Sentence Correction
- Data Sufficiency strategies
- Percent
- Integer Properties
- Powers/roots
- Algebra
- Geometry
As you can see, there's a big emphasis on math here. Your quant score of 39 suggests that you need work in this area as well.
I should mention that CR and RC questions probably have the lowest ROI. I'm not saying that you shouldn't prepare for them; I'm just saying that improvements take a long time, especially for non-native English speakers. For CR, be sure you understand the various question types.
Finally, over the next 3 weeks, try to take several official practice tests in order to perfect your time management skills and build your endurance. Remember that the GMAT is a test of your math and verbal skills
AND it's a test of your test-taking skills.
Cheers,
Brent
