1 NEWS' Joy Reid has put together a complete order of ceremony for tonight's big event - this will be the one you want to have handy as you watch along, with times, places and people, and everything in New Zealand time. Watch live coverage of the wedding from 9pm tonight on TVNZ OnDemand and build-up from 5pm.
On TVNZ 1, action will start at 5pm NZT with Prince Harry and Meghan: Truly, Madly, Deeply.
Joy Reid will be live from Windsor during the 6pm 1 NEWS bulletin, bringing you all the latest before the ceremony begins.
At 7pm Meghan Markel: The First 100 Days will screen, followed by An Invitation to a Royal Wedding at 8.05pm.
The 600 wedding guests will meet not far from the Castle and then be bussed into the Castle grounds from about 8.30pm NZT.
While they wait in St George’s Chapel there will be classical musical items which have been chosen by Prince Charles.
At 9.05pm, the BBC's live coverage will begin on TVNZ 1 - you can also watch live on the 1 NEWS Now homepage.
Meghan Markle will leave her overnight accommodation at a stately home nearby sometime after 10pm NZT and travel by car with her mother Doria Ragland which will at points be filmed and heavily publicised.
Then, back to the chapel ... at 10.25pm NZT members of the Royal Family will start to arrive through the Galilee Porch at the alter end of the chapel and guests will stand as they are taken to their seats.
Prince Harry and his best man Prince William arrive through the main entrance about 10.40pm NZT.
They’ll be followed a few minutes later by their father Prince Charles and his wife Camilla but they’ll enter, like other members of the royals, through the Galilee Porch.
Meghan Markle’s mother Doria Ragland, who will have travelled to the Castle grounds with the bride will walk into the church about 10.45pm NZT.
As is tradition, the Monarch is the last to arrive before the bride, she will enter through the Galilee Porch.
Meghan Markle will meet the ten bridesmaids and page boys and travel round to the front of the church, walk up the vast number of steps and right on midday she will start walking up the aisle.
Like any couple getting married, Prince Harry and Ms. Markle have taken a great deal of care in selecting all elements for their service.
It will take an hour and will be led by the Dean of Windsor, and officiated by the Archbishop of Canterbury Justin Welby.
The sermon will be given by US African American Bishop the Most Reverend Michael Curry.
Then they’ll say "I do" and express their vows, however they've chosen not to use the words "obey" in them.
Rings will be exchanged, and Prince Harry has elected to wear one - (his brother Prince William does not).
A reading will be carried out by his mother Princess Diana’s sister, the Lady Jane Fellowes.
Throughout the service there will be musical items performed by the choir of St George’s Chapel, accompanied by an organist, there will also be items from the BBC National Orchestra of Wales, the English Chamber Orchestra and the Philharmonia, the Kingdom Choir, State Trumpeters of the Household Cavalry (Prince Harry’s former army unit) and the British Cellist Mr Sheku Kanneh-Mason, who won the 2016 BBC Young Musician of the Year award.
At midnight NZT the couple, now husband and wife, will curtsey and bow to the Queen then down the aisle to walk out of the church onto the chapel steps where it’s believed the couple will have their first kiss as a married couple.
Once outside, they’ll first be greeted by about 200 members of the charities that Prince Harry and Meghan Markle are affiliated with who've been invited into the prime spot.
Also inside the castle grounds but just around the corner about 2500 members of the public will be waiting for them, a mixture of chosen people affectionately dubbed the "golden ticket holders" from the town of Windsor, the Royal Household and key volunteers from around the UK.
The couple will leave the castle grounds and start their procession in an open top carriage through the narrow streets of Windsor watched by thousands of adoring fans.
Then they'll head back up to the castle along the Long Walk lined with more members of the public and head back into Windsor Castle for their first wedding reception at 12.50am (Sunday morning NZT).
The procession route holds about 115,000 people and if more people than that arrive in the town, they’ll be redirected to big screens in local parks set up for the royal occasion.
The couple will have a wedding reception hosted by the Queen in St George’s Hall, then another more intimate one with 200 friends and family at nearby Frogmore house in the evening hosted by Prince Charles.
It's at the evening event where it’s expected there will be some star-studded musical items including the Spice Girls.