More than your marks, its your All India rank that decides whether you will get into IIT Bombay or not, because each year difficulty of paper changes and so does the marks. Since you are from general category, you should target a rank below AIR-15 (All India Rank) to confirm your seat in IIT Bombay.

I would suggest that you have plenty of time for UCEED 2019 preparation so work hard and give your best shot.

ALL THE BEST!!!!!