ovulation and DPO question

Courtney • 👼🏼 2-26-17 and now our Rainbow baby is here! 6-2-18 Carter Logan Freeborn 🌈👶🏼 and Easton Kent Freeborn due 7-26-19
Hi ladies :) if I had an LH surge CD 17, what would I count as 1DPO? Today or yesterday, currently at CD19 now. I'm new to tracking so any help would be nice. Thank you :)