Is there a set time for the Wigobi to be correct?

While looking into Wigobi, I unexpectedly became curious about these minor details.

I know that it is used once a week, but
I was wondering if I had to stick to the day or time exactly.

The time is fixed on weekdays, but
My daily routine tends to change a bit on weekends.

I am also wondering what to do if I happen to forget and use it later than usual.

From the perspective of someone just starting out
I want to start by properly learning these basic usage methods 💉