"The waistcoat is one of the few articles of clothing whose origin historians can date precisely. King Charles II of England, Scotland and Ireland introduced the waistcoat as a part of correct dress during the Restoration of the British monarchy. It was derived from the Persian vests seen by English visitors to the court of Shah Abbas" (taken from wikipedia). Good to know where this layering piece comes from, but even better is to wear it. As temperature is rising you easily can break up your 3-piece suit and wear your vest separate. Dont't waist time just your coat.