There are written references to bagpiping at weddings in the early 1600s in Scotland, and there is no way of knowing how old the custom may actually be. Almost every European country has an early form of the bagpipe that may have been used in this way. Often in current times, having a bagpiper present at a wedding is a way for the bride and/or groom to celebrate, honour and connect with their Celtic roots . . . or simply do something different.
Other times, the couple may not have any known Celtic connections, yet they still want bagpipes at their wedding. Once you've made the decision that bagpipes are a "must have" part of your wedding, the next step is to determine how and when. You may want the piper to provide all the music, or surprise the guests when escorting the bride and groom out of the ceremony.
Being one of the finest Sydney bagpipers I am happy to suggest for you:
Play outside as guests arrive or leave.
Play indoors before ceremony as a prelude - pipes alone or with an organ.
Play for the entry of the bridal attendants.
Play for the Bride's procession.
During the wedding as a solo or to accompany lighting the Unity candle.
Play at the end to escort the Bride and Groom out of the ceremony.
Play for 5-10 minutes and then lead guests to reception or to their cars.