How many DPO?

Ka

This is my first month charting and I’m trying to determine what day I ovulated. My OPK was positive on 10/19 so normally I would estimate the following day (10/20) but I know those are only accurate within 12-36 hours (10/20-10/22) so maybe it was later and that makes me 10 DPO today? Which temp day indicates ovulation? The first higher temp? The day after that?