Unlike other royal weddings, the day will not be broadcast on BBC, with ITV's This Morning instead taking over the coverage.
Princess Eugenie and Jack Brooksbank have been spotted driving up The Long Walk into Windsor Castle on the eve of their Royal Wedding.
Eugenie was also full of praise for her sister, Princess Beatrice, who will be her maid of honour.
Once married, Princess Eugenie and Mr Brooksbank will be taken on a short carriage procession along part of Windsor High Street.
Prince George and Princess Charlotte will be among the pageboys and bridesmaids at the wedding of Princess Eugenie, Buckingham Palace has said.
"We're hoping she's going to have a great day and we're very pleased that she's shared her day with us".
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The queen's luncheon is expected to be a quiet, muted affair - reflecting the 92-year-old monarch's advanced years - with the nighttime shindig seen as a chance for the younger generations to step out in style.
The Dean of Windsor will officiate the ceremony while Italian tenor Andrea Bocelli will perform during the service.
"Although Princess Eugenie's engagement ring is reminiscent of Catherine's with the large centre sapphire and diamond surround, it's a classic design for a royal engagement ring and not likely an intentional similarity", royal commentator Eloise Parker said.
On Twitter, followers can watch the stream on The Royal Family and Duke of York live Twitter pages. "It's very nerve-wracking because you want it to be flawless but then you realise that you're going to be with the person you love forever and nothing else really matters".
About 38,000 people signed a petition, organised by campaign group Republic, against taxpayers' money being spent on the occasion.
Michael Taylor, a drummer from Chicago who toured Windsor Castle on Wednesday told the Associated Press that he had "no interest" in the October 12 wedding.
Only a few Halloween face masks feature Eugenie, though some shopkeepers say that will change in the hours ahead of her wedding.