Working night shifts

Hello everyone,myself and my fiancé are ttc #1 at the moment. We have been trying a few months now but nothing yet. I'm a little confused as to best times of the day to do ovulation testing- because I work night shifts,  (also makes BD a little more difficult to do!) I'm not sure what time of day/night to do them? Also I know for pregnancy tests people say it's best do it in the morning as HCG is highest then, but does that apply for me working nights too?! #confused!