Congrats on making it through the first day. I always find the first few weeks nerve wracking. In some ways it is a lot of fun because you learn new things and you have someone showing you what to do. In other ways it is totally unsettling. Hard to be the "new guy." Even when I am moving into a field I have experience in it still feels like I am brand new and silly. I try to imagine how I will feel in two months.