BBT/Chart Help

Malina

This is my first cycle charting. Woke up at 2:30am and took temp in case I couldn’t fall back to sleep. It was something like 97.4, a big drop which would indicate period coming. Went back to sleep, took temp at 6am and temp is 97.88. I dont know which is the correct one to use?? My period was supposed to start yesterday and I have all the PMS symptoms, plus dizziness, which is new. Any advice??