Temping- Same time every day, or same hours sleep?

In order to get your most accurate bbt, is it better to take your temperature the same time every day, or after a similar # hours of sleep.

For example, weekdays I always go to bed around 10pm, and test at 6am. On a weekend, if I don't get to bed until 1am, is it still better for me to test at 6am or closer to 9/10am?

(This happened to me last night, I happened to wake up around 6 on my own, and my temp was 96.72, but when I went back to sleep and tested again around 10, it was 97.79 - not sure which temp to log!!?!?!)