Oh man I am so jealous! Three people from the company I work with are supported to go there. I missed it because I completely got the date wrong. First timers or not, just approach people and started asking what they work on. Your PhD is in math, so there are so many things to talk about/suggest/brainstorm with people. Don't sabotage conversations, I find that be a great listener really help in engaging in conversations across multiple topics solely because you've heard some common terms being thrown around. Relax and have fun!