What time do I take my bbt if I work 11pm to 7am and sleep from 8am -4pm sometimes later? Please help....?

I am 31 and trying to have my first baby. If I work night shift from 11pm to 7am 6 days a week and sleep during the day. What time would I take my temp? I want to make sure I get it right so any advice would be helpful. My sister has been helping me by reacting my cycle and watching for my ovulation days so I can make time at the right time please. Can anyone offer insight into this issue I am having I am extreamly ready to have a  baby.