One thing to keep in mind is that schools, including Princeton, will assess your improvement (both in terms of grades and of the rigor of your courseload) over your 4 years in high school. In fact, many schools tend not to look at your freshman year with much weight, as they know that freshmen sometimes need time to adjust. I would say not to worry right now, but PLEASE tell your parents not to pressure you too hard. It really can be a source of unbearable stress, and it certainly won't help you appreciate high school (or even do well in courses). On the other hand, if Princeton is a goal that YOU want to set, then this can be a source of motivation. Still, you are young, so keep and open mind!