I am in the same boat. I work swing/night 16 hour shifts twice a week, then an 8 hour shift once. It throws me off because I'm asleep when most people are eating breakfast and lunch. When I fast, I do it from the time I wake up to the time I go to bed. For example, I'll have my 'breakfast' at 1 pm after I wake up around 12:30. I'll take lunch around 7pm, and dinner usually around 5 am the next morning. I sleep from 8am to 12:30 pm on those days. Then I won't eat until 5 am (or upon waking) the next day. Just make it work for you. It really doesn't matter as long as you try not to eat right before laying down.
Grok On! <3