Confused BBT

I recently purchase a Femometer and just received it today. Reason for me to buy this thermometer is because I was diagnosed with PCOS, and other fertility issues last year and have been ttc. Well, I opened the Femometer and took my first temp (97.13) and logged it. Then, I was thinking best 1 out of 3 second was 97.8 then 97.99. What do I do in this situation? I took all within the seconds of each other. Please help?