Diclaimer: I joined BITS Pilani, Goa this year for my BE, and I’ve been here for around 10 days at the time of writing this answer.
It’s common knowledge that the Goa campus is the smallest of the three campuses in India. Even then, I’ve already started feeling the pain of walking all day and night around the campus (we’re not allowed to keep cycles).
After reporting for hostel allotment, and before the classes actually start, you’ll have 2 to 4 days to explore the campus and meet new people, depending on when you choose to arrive, before classes start.
Firstly, I’ll recommend you to get outside your room and meet new people. Just talk to everyone you meet on the way. That’s how you’ll make friends. Don’t hesitate, almost none of the people know each other from before and everyone’s looking for new friends to make. Eventually you’ll filter out the people you’d actually want to spend time with later on, but it’s imperative that you make as many acquaintances as possible.