What temp to use?

First month tracking BBT. I take my temp at 6:20 each day. This morning something woke me up at 5:20 so I took my temp and it was 97.22. I stayed in bed and fell asleep approximately 15 mins later and woke up at my 6:20 temp alarm. That temp read 97.33. Now I’m not sure which one to use.

* I have the earlier time saved in FF now, but not sure if I should use my regular 6:20 time since I didn’t get out and bed and went right back to sleep. It does make a difference in the amount of variation I did so I’m concerned it would throw it off.

I have quite some variation in my temps, even when taking them with an alarm. Is this typical to see such big variations like this?