First attempt 640. Retake the GMAT? Please tell me ASAP!

Hello everyone! Firstly, thank you for taking the time to read this. Any advice will be greatly appreciated especially if you can tell me ASAP as I don't have much time to make my decision!

I took the GMAT on December 03, 2019 and scored a 640 (V35/Q42/IR4) on it. I am not very happy with my score as I'd studied for around a month for the exam. However, as I had studied Accounting and Finance in my Bachelors, it was a long time (since high school/first year college) that I'd done math questions like probability, factorization, rates, ratios etc. A lot of time went in just revising these topics and doing the Manhattan sentence correction book. I studied mainly from only the Official guide 2019 and the Official Guide 2013 (though nearly half of the quant questions are similar to the Official Guide 2019) and before the exam had a good grasp of most of the Quant questions in both books. I'd have liked to do more material like Manhattan's Advanced Quant book but ran out of time towards the end. I actually scheduled my exam for December 03 back when I'd just started studying for the GMAT in November.

As I am applying for Masters of Finance programs (Degroote School of Business, McMaster University), I am wondering whether this score of 640 (V35/Q42/IR4) will be considered competitive for the MFin program at Degroote. They have 3 rounds for international students and while the first round has passed (December 01, 2019), the second round of admissions deadline is January 15, 2020 and the third round of admissions deadline is February 20, 2020. Now since today it is already December 06, I feel that even if I do retake the GMAT, it will take GMAT 3 weeks to send my official report to the Degroote school of business and it must reach the school BEFORE the second round of admissions deadline of January 15, 2020 for me to be considered in that round for admission. That means I should at most take the GMAT exam by December 24, 2019 and that gives me only 18 days more from today to study for it and improve my score. If anybody can give me any advice regarding how competitive my score of 640 (V35/Q42/IR4) is for the MFin at Degroote, I'll be extremely grateful. Also, is it advisable to take my time with the GMAT studies and target the third round of admissions deadline in February 20, 2020? The extra time would definitely help me to improve my score as compared to taking it now on December 24. But I feel that'd be risky targeting their final deadline of February 20 and feel that since January 15 is already their second round of admissions, I should apply by then and not risk waiting till February.

The mean (not median!) GMAT score of Degroote's MFin program is 676. So I'm 36 points below average. I've got mostly As and A- in my 3rd and 4th year of my Bachelors in Finance and Accounting from the Robert H. Smith School of Business, University of Maryland, College Park. My 3rd and 4th year CGPA at Smith was 3.67 (I got 4 Bs all in Accounting courses like audit and tax which brought down my GPA). I've also completed the US CPA exams. Had a straight 4.0 CGPA in my first two years of college though that was at a Community College (I think MFin programs might not care for community college coursework). My professors at the Smith School have said they'll write me very strong recommendation letters. I think my CGPA of 3.67 at Smith and the fact that I've passed the US CPA exams should at least demonstrate to Degroote's MFin that I'm capable of handling quantitative coursework even if my GMAT is 36 points below their average. But what do you all think? Should I retake the GMAT by December 24 to apply for the second deadline or retake the GMAT in January and apply for their final deadline of February? Or just concentrate on the rest of the application (Statement of Purpose) and pray that my GMAT of 640 is good enough for the second round of admissions. Also, I asked Degroote if applying before the second round of admission of January 15 would increase my chances of admission as compared to applying before the final deadline of February. They just said "We cannot say that your chances would be higher. Depends on the applications."

More information about my actual GMAT exam (including ESR):
During this past month, I didn't really use much of material besides doing both the Official guides 2013 and 2019 as mentioned, the sentence correction of Manhattan prep, the free exam of Manhattan Prep and one of the 2 free exams that mba.com provides us with. I scored a 630 on the mba.com practice test in the first week of November and a 650 on the Manhattan GMAT test in the second week of November. Felt kind of weird when after nearly 3 weeks of study from the dates of these mock tests, I managed to only get a 640 (between these two mock test scores). I did order the ESR and found that I scored a 90 percentile in the sentence correction questions (thank you, Manhattan SC!) but 65 percentile in reading and 49 percentile in CR. I feel I could have done a lot better in these two sections as just before my actual exam, I had completed many CR and RC questions of hard levels that I managed to get correct though CR was always my weak point. I think on the test day I took math first, wasn't too happy with my performance and that negatively affected my mind when the verbal section popped up. Plus, I'd hardly slept the night. I screwed IR as I spent too much time on one question and had to actually rush through the rest of them. Very bad timing on IR on my part.