LH rising 3 days before period

I have seen some people have been experimenting using opk tests when due there period and it showing a positive and they also got their bfp and how the lh test could be related.

I know to test properly use a pregnancy test but i am nervous after a chemical and it’s early so this is satisfying my need to test until my period date so please no moaning, I’m just curious.

Has anyone experienced this? My baseline Lh is usually barely visible but I’m 10 dpo (confirmed) and opk is reading almost positive. Has anyone else tried this?