Hi Manuel,
First off, a 650/Q42 is a solid Score, so it could be enough to get you into your first-choice School. Many Test Takers spend 3 months (or more) of consistent study time before they hit their 'peak' scores, so if you're studied just 3 weeks, then you should not expect to have mastered any of the concepts just yet. By extension, you might naturally improve as you continue to study.
IR has a lot in common with Verbal CR, so with a V38 you likely have strong CR skills - and thus a strong IR performance is a natural extension of those skills. Most Business Schools don't place much (if any) emphasis on an Applicant's IR Score, so scoring lower on your next attempt would likely not impact your application.
Since you have a specific Program in mind, you would likely find it beneficial to speak with an Admissions Expert about your overall profile and plans. Those Experts should be able to answer your Admissions questions and help define the specific areas of your profile that could use some improvement. There's a Forum full of those Experts here:
https://gmatclub.com/forum/ask-admissio ... tants-124/Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on how you've been studying and your goals:
1) Did you take the At-home GMAT or did you take your GMAT at a Test Facility?
2) How many hours did you typically study each week?
3) What study materials have you used so far?
4) On what dates did you take EACH of your CATs/mocks and how did you score on EACH (including the Quant and Verbal Scaled Scores for EACH)?
5) What application deadline(s) are you facing?
If you took your GMAT at a Test Center, then you might also choose to purchase the Enhanced Score Report. While the ESR doesn’t provide a lot of information, there are usually a few data points that we can use to define what went wrong on Test Day (and what you should work on to score higher). If you purchase the ESR, then I'll be happy to analyze it for you.
GMAT assassins aren't born, they're made,
Rich