When that may happen, however, is still a guessing game. The Duchess of Cambridge has said the baby is due sometime in mid- to late-April, but beyond that, public clues are slim.
Parking restrictions are in place around the hospital until April 30 and media won't take up their places outside until the Duchess has gone into hospital.
That's in part a result of a desire to avoid the media madness that preceded the birth nearly two years ago of William and Kate's first child, Prince George.
So far, this time around, the Great Kate Wait does seem more subdued.
Still, there is anticipation around the pending birth of a prince or princess who will be fourth in line to the throne. Here's what we know so far.
Where is Kate right now?
Reports say Kate and William have returned to their home at Kensington Palace in London after visiting with her parents at their home in Bucklebury, just west of London.
Kensington Palace is a short car ride from St. Mary's Hospital, where George was born on July 22, 2013.
When is the birth likely to happen?
While Kate has indicated the baby is expected in mid- to late April, the simple answer is we don't know.
All manner of speculation has surrounded various possibilities, ranging from whether the child might arrive on the 89th birthday of great-grandmother-to-be Queen Elizabeth, which was on Tuesday, or on William and Kate's fourth wedding anniversary, which is April 29.
One headline in the British media suggests the due date was actually yesterday or Thursday. Much speculation has also focused on the upcoming weekend, particularly April 25.
Odds on one betting website right now favour Friday the 24th.
Where will the birth take place?
Kensington Palace has said the newest royal will be born in the private Lindo wing of St. Mary's Hospital, where George was born. William and his younger brother, Harry, were also born there.
Hospitals outside London are also reportedly on alert for the possibility of a royal birth.
One is in Reading, not too far from the home of Kate's parents. Another is in Cambridge, north of London, and is not too far from Anmer Hall, William and Kate's country home in Norfolk.
How will the world find out?
So far, all indications are the birth will be announced via the Royal Family's social media channels, such as Twitter.
Timing is unclear — last time, the announcement came four hours after the actual birth.
The House of Windsor is also steeped in tradition, and beyond the digital announcement, the familiar royal birth announcement is expected to appear in relatively short order on a piece of official stationary carefully displayed on an easel in front of Buckingham Palace.
Who will go to visit the new family in hospital?
Some speculation has focused on whether Prince George may make a rare public appearance going into the hospital to see his new brother or sister.
George's public appearances have been few and far between, with most of the high-profile ones happening during a trip with his parents to Australia and New Zealand in April 2014.
It was also noted at the time of George's birth that the first visitors to see the new family were Kate's parents, Carole and Michael Middleton, followed by William's father, Prince Charles, and his wife, Camilla, William's stepmother.
Uncle Harry might even have a chance to stop by if the baby is born this weekend — he's due to make a quick trip home from his final military assignment Down Under.
What names might the baby be given?
Again, this is an area of intense speculation based on no real royal insight.
But that hasn't stopped people from talking, or betting. Alice remains the favourite for a girl's name among those who put down money with some British bookies. Arthur is a favourite on the boy's side.
Still, it's most likely the names chosen for the baby will have appeared at some point on the Royal Family tree — even if bookies are willing to offer odds of 500/1 on monikers such as Mercedes or Chardonnay.
What happens after the baby leaves hospital?
All indications are William and Kate will go from hospital to Kensington Palace for a short period of time before taking their growing family to Anmer Hall.
Kate's mother is widely expected to play a key role in helping her daughter and son-in-law settle in with the newborn.
William conveniently will be partway through a six-week unpaid leave from his new job as an air ambulance helicopter pilot for Bond Air Services, which will see him based not too far from Anmer Hall.