You may or may not get a First Visit button on check in. If it is not given to you automatically, ask the CM for it at check in. You will get well wishes, but that is about it, most likely.
We visited last week and I noted on our reservation that it was our 40th Wedding Anniversary and DS 33rd birthday. We did not get anything special at all, including birthday or anniversary buttons.
It was okay because I knew not to expect anything special. We had a wonderful week and enjoyed every minute.
So if you get something beyond a well wish to you be surprised.