Dream job or dream schedule??

Hi everyone! I just moved to Florida and took a job at one of the academic medical centers in which I am in week one of orientation for. This is for a 12 hour day shift position in surgical oncology. My passion in nursing is bone marrow transplant. I moved from a BMT unit and loved it so much, hoping I could find another BMT position in the future. After accepting the job, I got a call for an interview on a BMT unit at a hospital solely devoted to oncology, which is basically my dream job. I took the interview and they have made me a job offer for 12 hour night shift (no weekends), $1 more an hour than I'm making at the other hospital, with a promise to be the first person to switch to day shift. I expressed my concern to the manager about being on nights again, she said she understood and would promise to call me when a position opened on days before hiring or transferring anyone else, if I decided not to take the night shift position.

Quickly, I'll give a little background on why taking a night shift job is a dilemma for me. I worked night shift for a year at my previous job. During this time I developed migraines, random episodes of vomiting (4-5 times over the course of the year), lacked motivation for anything, and just felt like pure crap. As soon as I was off night shift I hadn't experienced another migraine since and finally feel normal again. I vowed to never go on night shift again.

However, I'm concerned that I'm going to start this new job on the surgical oncology unit and need to quit within 1-6 months, when a position opens on the BMT unit. Would I be better off taking the night shift position with the patient population I love and waiting for a day shift position to open, or work days at my current hospital until I can transfer? I have no way of knowing how long it'll be and I'd think it would be more heavily frowned upon to leave after such a short time, than just leaving during orientation when they aren't counting on me for staffing, etc.

I need some advice on how to handle this situation, please, I'm stressing over this big time!