Time of day for OPK?

Very confused about the best time of day to use opk. Almost everything I’ve read online (including Glow articles) says that using FMU is not necessary, and that surges are more common in the afternoon- and that the most important thing is to test at the same time each day.

I started using ClearBlue Advanced Digital yesterday, cd6. (My cycle is a little thrown off bc I had a mc in December😞, so I wanted to test early just to make sure.)

I’ve tested yesterday and today around 2:30 pm. Today (cd7) I was surprised to see High results already. I know it’s somewhat common to have many High days before peak (this will hopefully be Baby #3, so not my first rodeo) but when I read the fine print in the directions, it DOES say to use FMU, and that if you don’t, you could get unexpected High results. Can anyone shed some light on this? I pulled the stick out and the test line doesn’t look very dark at all.