It's such a personal thing. I admit I tend to peek at the scale every few days or so. It's a good sign when I do that, it usually means I feel on track.
My official weigh in's are every other Friday. I weigh in on whatever day isn't my pay day. I record my weight on a log sheet I made with dates of every other Friday until like 2015 (hopefully aren't I?). I have a column for goals, and once I weigh in - whatever it is- I make my goal to be 4 lbs below that for the next two weeks. Although, now that I'm exercising, I'm going to change that to 6. That's just what I do. So far it's worked, I've been chugging along despite the odds
Sometimes I'd meet my goal, sometimes I wouldn't. I would just readjust and hope for better.
Anyways I like weighing in twice a month because I feel like if I screw up I have more time to make things right, a week seems tight to me.