AYUSH198:
A 720 is a fantastic score - congrats!
It would be helpful to know more about your profile besides coming from an overrepresented demographic. While there are no exact figures, it can make a difference as to how you define "overrepresented." Also, to which schools are you planning to apply?
As for the GMAT, would another sitting for the exam make a difference? To bump up, say 20+ points, would you need to put in a lot of time or just simply take the exam again? What was the split in your score? Could you focus all on either verbal or quant while holding the other constant?
The applications for the upcoming season aren't released until end of July/early August. While there is information you can do ahead of time (campus tours/visits/info sessions, resume/CV, etc.), you really do need to wait to start until you are aware of the official essay questions and requirements. The questions can change year to year and it would be a bad idea to have to redo work, especially if you are crunch for time.
As you can tell, there are a lot of nuances to determining whether it makes sense to focus on the GMAT or start the application process. If you wish, please sign up for a free consultation so we can discuss this matter and your overall application strategy in more detail.
https://admissionado.com/free-consultation/