I've only used nibs once, and I tossed them into the boil with about 10 minutes left and it worked for me. I haven't experimented with using them in the fermenter as something like a dry hop or even in secondary yet, so there's that, but if you toss them in with the boil it will give you some chocolate flavor.
Edit: Also worth noting - they were floating at the end of the boil so I went ahead and transferred them into the primary. They were in with the beer for about 2 weeks before I transferred it into secondary to add vanilla beans.