Well we know it does not seem like an important issue or topic, but it is! It is as relevant as doing your zipper right before leaving the house to avoid embarrassment, so see below the rules involved for suits buttoning.
1. One-Button Suit Jackets
These jackets should ALWAYS be buttoned when standing and unbuttoned when sitting down, so that it doesn’t crease.
2. Two-Button Suit Jackets
The top button on these jackets should be buttoned at all times, especially when standing; unbutton only to sit and leave the bottom button undone to avoid adding more weight to your mid section.
3. Three-Button Suit Jackets
You can choose to open the top button while standing, ensure the middle button is always in place and do not fasten the bottom button.
4. Double-Breasted Suit Jackets
For double-breasted jackets, all the buttons should be in place at all times.