At noon (7pm Hong Kong time) Thursday, 42-gun salutes will be fired across the country to mark the queen’s “official birthday” on June 11.
Selected Royal Navy ships at sea will also fire their guns, along with the Grand Battery in Gibraltar off Spain.
An hour later, the Tower of London will salute with no fewer than 124 rounds.
Completing the parade is a six-minute fly-past over Buckingham Palace with more than 70 aircraft from each branch of the armed forces.
They include the Red Arrows, the Royal Air Force’s aerobatic team, and a collection of iconic World War II planes including three Spitfire fighters and a Lancaster bomber.
One number will be down on previous gala occasions: the royal family members watching from the Buckingham Palace balcony.
Appearances are restricted to “working royals”, which means no Prince Harry and his wife Meghan, nor the queen’s disgraced second son Prince Andrew.
More than 2,800 beacons will be lit Thursday night across the UK, including atop the country’s four highest peaks, as well as on the Channel Islands, the Isle of Man, and British Overseas Territories.
Flaming tributes will be seen in 54 Commonwealth capitals across five continents, from Tonga and Samoa in the South Pacific to Belize in the Caribbean.
Even France is joining in, with buildings on the coast facing England set to be illuminated.
London bridges and landmarks will also light up, along with cathedrals across England.
A national service of thanksgiving takes place at London’s St Paul’s Cathedral Friday, featuring a rare ringing of the Great Paul bell.
At a gigantic 16.5 tonnes, it is the largest bell ever cast in Britain. Its mechanism broke in the 1970s, but it was restored to its former glory last year.
On Saturday, around 22,000 guests including 5,000 “essential workers” such as medics and emergency services staff will attend a BBC concert at Buckingham Palace.
The 2.5-hour musical extravaganza will include performances by Queen + Adam Lambert, Diana Ross, Alicia Keys, Nile Rodgers and the Italian tenor Andrea Bocelli.
For Sunday, more than 70,000 people have registered to host “Big Jubilee Lunches”, with 10 million expected to share food and friendship with their neighbours, according to the UK government.
Prince Charles and his wife Camilla are expected to attend one at The Oval cricket ground in London, where a six-metre felt artwork will be on show featuring a design of the “Platinum Pudding”.
The pudding that won the competition for the occasion – a lemon Swiss roll topped by an amaretti trifle – was chosen from nearly 5,000 entries by amateur bakers.
The recipe includes 13 eggs, takes “over two hours” to prepare, and serves 20.
The celebrations culminate Sunday with the “Platinum Jubilee Pageant” – a public parade through central London.
Some 10,000 people are involved in a musical and creative display of how British society has changed since the queen began her rule over what was a very different country in 1952.
Then, the coronation sparked a boom in sales of television sets. Today, a billion viewers are expected to tune in around the world to watch Sunday, climaxing with Ed Sheeran singing God Save the Queen.