This is the first time that VIT had to cancel its entrance examination and conduct admissions based on Board exams and JEE Mains. And it has also been announced that weightage will be given to JEE Mains score. While the marking and weightage scheme has not been announced yet, this answer is being written with general information. Once VIT releases any official information regarding the weightage and marking scheme, we would be able to answer your question with more relevant information. What is important is to know is admissions to VIT all campuses will be conducted without reservation and all seats are considered Open Merit. So even if you have scored less than 50 percentile in January session but can turn the tables around and score good in September session, you might still have a chance. But you need to really up your game and score more than 90 percentile so as to bring the average percentile to a better score. This might help you: https://learn.careers360.com/knockout-jee-main-april/