Positive OPK this morning! Plus questions

Bre • 26 - Married - Early MC June 2017 - Rainbow Baby May 2018🌈💙- Due again March 2020

This is my first cycle using them. So tomorrow I will count as ovulation day and Thursday will be 1DPO, right? Or today ovulation day since it's so early and tomorrow 1DPO?

Who else got their positive OPK today? My AF is due Sept 13th! 😬

This is the first month I feel good about things since my early MC in June!