temping doesn't always suit everyone, and I know that you have different waking times, but I am pretty sure that FF says that as long you get 3 hours sleep and then take your temp it should be ok, after all, shiftworkers can take their temps too but just not sure what FF friend suggests, you could always go to the Q&A section on FF and see if that gives you any answers. And I agree with Rufalina about temping downstairs, they will tend to be higher so you should wait till the start of your next cycle before switching