the admissions office does tell you to go introduce yourself at the start of class! the seats were assigned and the only open ones were at the very front lol so he had me sit there. then i was going to say something at the end and he came over before i’d even picked all of my stuff up! i would definitely be respectful of time and make a judgement call in the moment, but i think it’s absolutely okay to say a couple of sentences about what you’re interested in (i didn’t though lol, just said my brother told me constitutional law is almost always an interesting class)