Ovulation test help

Does an ovulation test come back negative after you’ve ovulated? Because yesterday at 9am I got a very dark positive line. I then tested again at 4pm and it was quite a bit fainter (like several notches off from positive). So wondering if I ovulated somewhere between 9am and 4pm? I thought you ovulate 12-36 hours after positive result so just wondering if it means I ovulated super quick or what?