BBT help

Jessica

Trying to use BBT to confirm ovulation…but new to it. I went to bed at 9:30 and woke up to pee at 1:30am. Had no idea what time it was so I checked anyway and it was 98.0. Woke up again around 6am and checked and it was 98.1. Not a big variance but which tempt should I go with? What is the rule of thumb when temping? Longest sleep or when you get up for the day?