How often should I take pics?

I have taken some shots in my undies today (bleurghhh!) but wanted to take them so I can monitor changes in my body.

How often do you think I should do this to see a difference? Weekly, monthly?

Does anyone else do that? Xx

I'm taking mine after every lost stone

Last time on LT I took mine once a month and the difference is great to see, really spurs you on.