I like the tradition in the South, where there is a bridal shower about 2 - 3 weeks before the wedding....all the gifts are opened then. Then at the wedding, there is nothing to do but enjoy the wedding and reception.
That being said, like someone else stated, most of the time, the gifts are not opened at the weddings. They are opened upon the couples arrival back home, so I would take my time quilting the quilt. It will be a surprise for them.