this might help - got it from a site - recommend you button the suit as stated and unbutton it when you sit down ...
So now that you’ve picked out your suit, you have to know how to wear it. We’ll assume you know the basics of putting the thing on. (Yes, the jacket part goes on top.) And this brings us to buttoning. It is a historic dilemma, faced by every man. Here, for you, is our easy-to-remember rulebook:
Two-button jacket: Button the top button, only, ever. Button the bottom button and you’ll look like a stooge. That’s really all there is to it.
Three-button jacket: Button either the middle button alone or the top two. Important: the bottom button does not meet its hole.
