Period vs. ovulation

Maybe someone here knows - I have a regular 28 day cycle, every four weeks my period starts like clockwork. I track my ovulation too so I know when that happens. It usually occurs on Day 16 or 17 of my cycle - two weeks and two or three days after the start of my period. But that also means that I would have a missed period before I can reliably test if I’m pregnant. Do you think missing my period is a valid sign of pregnancy despite that first missed day only being 10 or so days past ovulation at best?

Maybe a better question - how early can you actually get a positive test?

Thanks for any input!