The newly-wed royal couple will be doing a tour of the city centre of Windsor, around 41 kms from London, in a traditional horse-driven Ascot Landau carriage after Prince Harry, 33 and Markle, 36, tie the knot at St George's Chapel in Windsor Castle.
More than 250 members of the armed forces will take on ceremonial duties on the day, lining the streets of Windsor, providing an escort for the procession and flanking the entrance to St George's Chapel.
Twenty-eight members of the Household Cavalry took their places in a lineup on the staircase at St George's Chapel, according to a Ministry of Defence spokesperson in Windsor.
Twenty-six mounted members of the Household Cavalry rehearsed the procession route through Windsor, escorting the carriage that will carry the couple on the day, the spokesperson said.
Prince Harry has a close relationship with each of the regiments and units participating on his wedding day, according to Kensington Palace.
"Led by Director James Vivian, the St. George's Chapel Choir were in rehearsal for the wedding of Prince Harry, and Meghan Markle," Kensington Palace said.
The palace had revealed yesterday that Prince Harry's niece, three-year-old Princess Charlotte, will be one of six young girls chosen as bridesmaids at the wedding. Her elder brother, Prince George, aged four, will be a pageboy among a total of 10 children chosen for the roles.
Meanwhile, some campaigners have handed over a petition to the UK Parliament to ensure the royal family pays for the enormous security costs involved in the royal wedding. The anti-monarchy campaign group Republic has gathered 32,000 signatures on an online petition calling for "no taxpayer funding for the royal wedding".
"The Palace claims the wedding will be funded by the royal family, but royal funding blurs the lines between private income and public money. So, whether it's the cost of policing paid for directly by us, or costs of the wedding ceremony, paid for by the royals, the taxpayer still ends up paying," the petition notes.
"There is nothing inevitable about the public spending on a royal wedding. If the royals don't want to pay a big security bill they could have had a private wedding in Sandringham or Balmoral," Republic chief executive Graham Smith said after handing over the petition to British MPs yesterday.
Local Thames Valley Police have said the wedding is expected to attract thousands of people from around the world to Windsor and that their planning is well under way.
"Visitors to the town can expect to see our officers, both armed and unarmed, our search dogs and our mounted section..," police said.
"A broad range of visible security measures are already in place, such us the extensive network of Automatic Number Place Recognition technology, Close Circuit Television and Hostile Vehicle Mitigation barriers," a statement said.