It has taken at least 12 months post bub for my stomach to be flattish. I don't think it will ever be the same once you have babies. I ended up being a size 7 due to illness after Caleb but my belly skin was still loose.
I think the secret is to be very selective with the clothes you wear. I reccon I tried on every style of jeans in Just Jeans one day to find the one that looked best on me