Hi taimoorjamal,
A 540 is a solid initial CAT score (the average score on the Official GMAT hovers around 550 most years). Many GMATers spend 3 months (or more) of consistent study time before they hit their 'peak' scores, so since you've been studying for just about 1 month, you should not expect to have mastered any of the content yet. Statistically-speaking, raising a 540 to the point that you can consistently score 690+ will likely require at least another 3 months of consistent, guided study - and you'll have to make significant improvements to how you handle BOTH the Quant and Verbal sections. Thankfully, the GMAT is a consistent, predictable Exam, so you CAN train to score at a higher level. You might need to consider pushing back your Test Date, but you don't have to decide on that issue either way just yet.
While you have not named any specific Programs, the Top 20 Schools that you might be considering are all highly-competitive, so 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/If you're still looking for a GMAT Course, then it's worth noting that most GMAT Companies offer some type of free materials (practice problems, Trial Accounts, videos, etc.) that you can use to 'test out' a product before you buy it. We have a variety of those resources at our website (
www.empowergmat.com). I suggest that you take advantage of all of them, then choose the one that best matches your personality, timeline and budget.
If you have any additional questions, then you can feel free to PM me directly at any time.
GMAT assassins aren't born, they're made,
Rich