Hello
Applying in R3 means your chances of getting selected will be very low. And most schools have three rounds, not all schools have four rounds. Giving GMAT in December end you will have very little time to write essays and prepare an overall decent application. And if at all, you are not satisfied with your score and need to take it again, there will be no time to retake it and prepare your application in time for R3. The best course of action is therefor to apply next year in R!. As far as your visa is concerned, you will only need to shift it to F1 once you have secured admission in a B-school.
Hope this helps
All the best
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