My official weigh-in day is first thing Monday morning after bathroom time before anything else.
Mondays are good for me. It's after a weekend, so I keep mindful and don't go "weekend crazy!" It keeps me thoughtful about the rest of the week, too.
Sometimes I get curious and weigh in other mornings or evenings, just to see. But, I never "count" those times. They're just for fun!
~Made of star stuff~