If you have been ACCEPTED into the program, you may list it on your resume:
RN/BSN Program, XYZ University
Expected date of completion: May 2014
If you have not yet applied to the program, or have not yet been accepted than you should not list it on your resume.
I disagree that there is no need to list it. Nurses with BSNs are more desirable to many facilities. Some will consider you for a BSN required position if you are already enrolled in a BSN program.
However, in this specific case it may not help you either way. The position is at a nursing school, and most likely requires a BSN because of the nature of the education you will be providing to nursing students. But it certainly won't hurt to list it.