All you need to know is wear conservative clothing. Such as jeans, t-shirt and shoes. Although more than likely you will not be asked to perform skills the first day, I was. A lot of bending over. moving around and laying down to have other students practice assessments on you. So, it's best if girls do not wear skirts and flip-flops with low cut shirts and guys do not wear shorts, flip-flops or a tank top. You can wear more casual stuff later in nursing school
once you get the routine down and what you will be doing each day. So, if you wear jeans and a t-shirt with shoes the first day you should be fine.
Along the lines of what to expect is you may feel like the professors are throwing stuff at you and you cannot keep anything straight and half the stuff they are talking about doesn't make any sense, this is normal DO NOT freak out. Bring a planner and write down all important dates (i.e. clinicals, simulations, skill days, academic classes, etc.). Also, print off all syllabuses before hand because this will be more than likely where your class and clinical schedule will be. You will feel totally lost and behind the first couple of weeks, everybody does. Just keep all important dates in a planner and study your tail off. Routine will come to you, but not for about a month of two.
Just be organized/prepared with all syllabuses and you should be fine the first day. Good luck!