I don't know anyone that was able to maintain their clients and go to nursing school
Working for a chain salon might give more flexible options for working around your schedule, but the clients might not be as flexible, since they might be working or going to school as well.
Working for a chain may at least allow for more walk-in customers, and maybe help increase the client base, for example, if you went to school during the day and worked in a chain from 4 to 9pm, you would be catching people that come off work.
If you wanted to try and work for yourself and go back to school, try to inform your clients about the change in hours as soon as possible. Make a printout of what your new hours will be. But also, you might find those hours might wind up changing each semester and that wouldn't be good for a personal business.