Chance Me for Georgetown

I’m an Indian student in Class 12, with basic sciences (physics, chemistry, mathematics, English and fine arts). I took the SAT two times, once had a 1270 in Class 11 and now I have a 1480. I have abundant extracurricular activities; I played the piano for my school orchestra 6 times, have performed at state level piano competitions, know programming (data science in Python, web development, game development in a variety of platforms), have got about 16 medals in SOF Olympiads etc. My weak spot is my Class 11 score. I got a 9.6 CGPA in Class 10 (decent score) but my results dropped to marginally passing in Class 11. I’ve since then getting very poor scores, partially because of my poor education system, and I wonder if it will affect my GPA, especially if I take SAT Subject Tests in Math and Physics and get a good score to compensate. Also kindly advise me whether I should wait for December to take my SAT Subject Tests or apply earlier, especially because my Pre-National Examination (conducted by the school as preparatory test for my Class 12 National Exam) will be conducted by December and I may get good scores in it.