Advise please, (Long)

I graduated from nursing school a little over a year ago and have been working on a tele/stepdown floor. I had originally hoped to get a job on an oncology or palliative floor at the hospital I am currently working at. However, none were available at the time since most of my clinical experience in school was on a tele unit I decided to go that direction. I have recently been getting an itch to move to oncology specificly but maybe palliative. I have asked a coworker who recently left the unit I work on how I should go about it. She told me that I should apply for the position I want and then let the nurse manager of the unit I would like to move to contact my current manager. THis is how I would plan on proceeding but currently there are no night shift positions posted. (I have to work night shift so that work doesn't conflict with school) Would it be inappropriate to email the oncology nurse manager with my desire to work on his unit on night shift? There are currently two day shift positions available but as i said before I need to work nights.