I used to work 6PM to 6AM (was a great shift for the summer heat in las vegas) but it sucked for me because sleeping during the day is hard. I remember being on a call, passing one of those bank themometers and it said 101 at 4:45AM, and I ended up working days for the next two summers, ugh.
I have always had a hard time sleeping during the day, in fact I have never been a late sleeper. The only thing I can suggest is staying up as late as you can (turn on ALL the lights) for two days before your shift starts. I used to cover my windows with black sheets and make it as dark as I could, and run a fan for some "white noise". I am assuming you get at least the weekend to get ready for this. Sleep during those days to get ready for your shift, just make sure you stay awake the same hours as you are supposed to work. It will suck, trust me, but when your shift starts you will be "semi" used to it.
Good luck.