Hi, I have exactly the same problem as you and have been recording my temps on a website. Interestingly though, despite it saying I ovulated this month, my blood tests say I didn't so I think my temping is misleading and I am not going to do it anymore.
I will just have to resort to pouncing on my DH randomly every week.
I would temp at 5am in the case you describe. I'm not charting fully at the moment, (no need so have got lazy, I just keep an eye on CM for my own interest lol), but I got into a habit of taking temp on first waking, even if the time varied within a 2 hour (or so) framework. My temp would follow the expected pattern with perhaps a couple of "odd" ones here and there and tbh I didn't even note the time after a while. What I did make sure was that I did it religiously every morning, even when it wasn't absolutely necessary - ie mid period, or after ovulation. That way it becomes part of your routine (and you get a prettier chart lol).
I'm still really confused about temping. Am using fertility friend which says
'Make sure you are taking your temperature at the same time every day, when you first wake up, after a solid block of sleep, and with a BBT thermometer.'
How do you do this when the time you first wake up varies by up to an hour day to day?
I am finding it impossible as i keep waking repeatedly between 4-6 due to dh snoring, ds waking early & stressing about what bloody time I should be take my temp My chart is a bit erratic & am sure this must be a factor.
So if for eg my usual waking time (before i started temping) was 7am, & today i wake at 5am but go back to sleep til 6am, do i:
a)temp at 5am as its after a solid block of sleep
b)temp at 6am as i didnt go back to sleep, even though its an hour earlier than my usual waking time
c) lie still in bed until 7am even though this means I've been awake a full hour before temping.
If anyone can clarify which is the correct way i'd really appreciate it. Thanks.