Corsets shift your organs I would recommend you do your research on them before putting one after giving birth. Your body may need time to get back to normal before using a corset. I recommend panty spanx.
I'm planning to get the wink post pregnancy compression girdle. It has great reviews and is on Amazon.com. It's a little spendy, but it is the only one I have found with such great reviews for working and being comfortable.
I don't remember exact brand but I got a velcro closure one off amazon for about 30 that I got to fit for right after birth and safety pinned it all the way down folded over for when I needed a size smaller I wouldn't use anything that has a panty type part to it just one that goes from ur hips to under ur boobs