It's up to you how often you want to check.

Whenever I was tracking mine on a regular basis, I used to take them every week on the same day, same time of day.

I used to have a lot of fluid retention, so I would check it first thing in the morning, every Sunday morning.

But, you can check it any time you want to.

I HATE it when I take my measurements or weight and not see a loss, now I wait until I "feel" like I've lost something or I can see a slight difference in my stomach, neck or forearms.

Oh, that's another measurement you might find interesting to track--your neck.

You've got me motivated, now. I think I'm gonna take my measurements today and start tracking them regularly again.