You haven't mentioned your Category. Nevertheless, in 2018 99.64 was the cut off for General Category, 99,42 was the cut off percentile for OBC, 96.18 was the cut off percentile for SC and it was 93.83 for ST Category. Now this is 2018 data and in 2020, AIIMS and JIPMER will conduct admissions through All India Quota based on NEET score. It is difficult to predict cut offs for AIIMS because all this while AIIMS conducted its exam for 200 marks and then released its score in the form of percentiles. While NEET is conducted for 720 marks and the results are released in the form of marks. To convert 99 percentil of 200 to marks out of 720 is difficult. And then this is 2018 data and cut offs change every year. Cut offs change every year depending on various factors such as no.of Candidates appearing for the exam, no.of Candidates qualified, top NEET score and difficulty of the exam. Your NEET score, Category and tie breaking situations decide your rank in the merit list. Considering all these factors for a seat in AIIMS Guntur under General Category, you atleast need 625 and for reserved Categories, you will need atleast 600.