There's little to suggest that
this is not Blaise's native state, by now; she's had the chance to ask the Bar for appropriately cut robes, and discovered the infinite usefulness of hair ties. After all, one must take advantage of these opportunities where one can.
But there is the fact that she appears to have acquired a small stash of those mints. The first one has yet to wear off, but she's still debating their usefulness back at Hogwarts.
Meanwhile, she's claimed a table, and is working on some upcoming homework. If she can get this Arithmancy essay and problem set out of the way while she's got all the time in the world, so much the better. (And if anyone wonders how she got it done so quickly... well, she was Sorted on her cunning as much as because she rejected all the other choices.)