ovulation test help

Dominique🌹 • 25.🌷 Mama to a beautiful baby boy ❤👶🏼

So I am new with ovulation tests and I was just wondering when is the best time to test? On the box, it's written to not test with fmu but I drink a lot of water in a day so it's diluted a lot. Does it have an impact like pregnancy test or it doesn't matter?