Calculating DPO

Jordan • 27 y/o. Baby #1. Due 12/10/17 👶🏼 💕
So according to glow, is the day of ovulation the day with the highest chance of conceiving? I monitored bbt and used OPKs back in January and this month I've only using glow and monitoring my CM. and it was on point! I'm starting to have waves of nausea, gas pain, and bloating. I'm just wondering if it's too soon to start seeing symptoms but idk how to count DPO