The former Beatle is expected to pay tribute to his late wife Linda, who died of breast cancer in 1998, in an emotional speech during the wedding reception at his London home.
But there will be no mention of his second wife, Heather Mills, whom he divorced acrimoniously in 2008, and whom his children are said to have never liked.
Yesterday Sir Paul, 69, and Nancy, 51, who is Jewish, visited the Liberal Jewish Synagogue near his home in St John's Wood, North-West London, to mark Yom Kippur.
The radiantly happy couple left the singer's home in a chauffeur-driven Lexus just before 5pm, with Sir Paul winding down his window to say to gathered wellwishers: 'Hi guys. Thanks for coming. We're looking forward to it. See you guys.'
Yesterday, final preparations were getting under way at the house before the arrival of guests who are expected to include Sir Paul's five children – adopted eldest daughter Heather from Linda's first marriage, photographer Mary, fashion designer Stella, son James, and youngest daughter Beatrice.
After the celebrations the newlyweds are expected to fly to America to celebrate their wedding with a second gathering at the Hamptons, where the couple with a combined wealth of £700 million both own homes.
Miss Shevell, who was a long-term family friend of Sir Paul and Linda, is vice president of her family's transport firm and has a 19-year-old son, Arlen, from her 24-year marriage to first husband Bruce Blakeman.