Only a few Halloween face masks feature Eugenie's face, though some shopkeepers say that will change in the hours ahead of her wedding.
Brooksbank, 32, has asked his brother Thomas to be his best man.
Because the wedding takes place on a weekday, and they are "minor" royals, it is unlikely to attract the 13 million United Kingdom audience of her cousin's wedding.
Despite large signs at the castle's ticket booth welcoming people to the wedding, many visitors seem unaware that Princess Eugenie, granddaughter of Queen Elizabeth II, will marry tequila company executive James Brooksbank Friday.
Eugenie, a director at London's Hauser & Wirth art gallery, and Brooksbank, who is European brand manager for Casamigos Tequila, which was co-founded by US actor George Clooney, met in the Swiss ski resort of Verbier in 2010.
Apparently, Eugenie has even allowed Jack to "be in charge" of the alcohol selection.
There are around 1,200 people invited to the wedding.
Prince George and Princess Charlotte will also play a starring role among the young helpers, along with Zara and Mike Tindall's spirited four-year-old Mia and Peter and Autumn Phillips' daughters Savannah and Isla.
"It was love at first sight", Princess Eugenie told This Morning.
She said: "I felt as though it could have all been nipped in the bud if everyone was included and we just all agreed to move forward with positive resolve".
Prince Andrew and Sarah, Duchess of York, are divorced, but remain close and have been seen together, including at Royal Ascot in 2015, along with their daughters, Princess Eugenie, centre, and Princess Beatrice, far right. And let's not forget their musical guests, including Andrea Bocelli, who will perform two pieces during the service, as well as the Royal Philharmonic Orchestra.
David Conner, the Dean of Windsor, will officiate over the vows and give the address.
There has been some criticism about the cost of security around the event, which will be paid for by the taxpayer like all royal events.
Again taking a page out of Meghan and Harry's book, the ceremony will be followed by a carriage ride outside of Windsor Castle.
Trevor and Tracey began dating in November 2017, and the film producer popped the question just weeks after Meghan and Prince Harry married in their lavish ceremony in St George's Chapel in May.
And in another freaky moment, the 53-year-old then bought royal merchandise from a nearby stall, including masks of Meghan and Harry.
While there are a lot of things that echo Meghan and Harry's wedding there are also some not so subtle ways she is trying to beat her cousin as well.
Princess Eugenie is the daughter of the Duke of York and Sarah Ferguson.