If you are wanting it to make your tummy look flatter soon after birth, I think focusing more on what you wear would be more effective and comfortable. There is no way I am putting something constricting on shortly after having a baby - bring on the wrap dresses and long sweaters
As PP said, these can help a lot if you have an incision and need extra support for loose muscles. But not as a way to lose weight or look trim.
Re: anyone ever used a belly bandit? is it worth it?
I used one with DS (bought used). You don't need to pay $$$ for the Belly Bandit- just any abdominal binder for extra support.
It does NOT give you a flat stomach faster. It can give support to weakened muscles especially if you have an incision.