BSN Program

Congrats on being accepted! May I ask, is this an accelerated program? Because that would certainly change my response a bit. But assuming this program is the "typical" 4 year track I will say that I've heard this from many nursing colleagues over the years. Doesn't matter if it was an Associates program, a Bachelors, Masters or Doctorate. Schools will often say students shouldn't work because they want you to focus on your education and they don't want to give you any false hope that the program is easy. Just like with any other school environment - some courses will be easier than others. For those that are easy, you may not have to study as much as those that are harder for you. The key is to set up a study program that works best for you. Map out your class schedules, assignments/tests/quizzes, and your work schedule. It may be a bit rough at first but soon you'll figure out what study schedule works best for you. Do this each semester as the courses will change. While it's nice to have a set work schedule, try to ensure flexibility in case you need to do additional studying for an exam or project. There may be semesters where all of your courses are difficult, so ha being that consistent and routine study program will certainly aid during those times. Also, look into different study m those such as reading and recording your notes. That way you can listen to them on your way to work or as you run errands. 
Hopefully some of this was helpful. Best of luck!