I was fortunate enough to not have to work while in nursing school. Each semester has its own set of challenges that will require you to spend more time on school work than you have done in the past. Working while in nursing school will depend on how you adapt to all the changes you will be met with. Like I said, each semester is different... soph 1 you are at school most days of the week and taking very challenging courses, as you progress you spend less time at school and more time in the clinical setting (again-very challenging courses) which means a lot of time spent on clinical paperwork. You need to make sure you have ample time to study and do assignment and schedule in some time to unwind. I would recommend you cut back your hours as much as you can get by with and re-evaluate how things are working out for you. Don't schedule work before a test and when you start clinicals, don't schedule work the night before or the nights after a clinical day.
Working and school will have to be re-evaluated every semester, remember the end goal... if you need to quit in order to do well, then do it. I honestly don't know how some people were able to work, but you have to do what you have to do. Look in to financial aid too, I was surprised to have gotten a pell grant for these past 2 semester (I have never qualified for one before).
And a little aside, your soph 2 semester is going to be the heaviest course load of the program-so keep that in mind when deciding to keep your job.