They might be the most important parking spots in the United Kingdom, nay, the world right now.

Any day now, a raft of yellow signs will appear outside a hospital near Windsor, which will prohibit loading, stopping or waiting.

While changes to traffic conditions in southwest London are not usually breaking news, when these particular notices are swiftly and mysteriously erected, it will mean — drum roll please — the official countdown to the birth of the royal baby has begun!

It has been widely reported the Duchess of Sussex will eschew the fabled $13,700 Lindo Wing in favour of a hospital closer to the couple's new pile, Frogmore Cottage.

The options are Princess Margaret Hospital, King Edward VII Hospital or Frimley Park Hospital in Surrey, which is where the Countess of Wessex had her two sproglets. Basically, they are all an easy dash from Frogmore Cottage when things start to happen.

We, the breathlessly waiting public, are still in the dark about when exactly the Sussex tot will make its glorious arrival in the world. However, once Meghan has even her first inkling labour might be about to start, we do have a pretty clear idea of how things will progress over the next history-making 48-72 hours.

Ready?

WE HAVE LIFT-OFF!

So, once Meghan's waters break, or those contractions start getting closer together, it's most likely she and Harry will be whisked to their chosen hospital in a discreet convoy of two Range Rovers. (This is the exact journey Kate has made three times from Kensington Palace to the Lindo Wing.)

MAKE ROOM FOR THE MEDIA

News will usually leak she has been admitted to hospital so the vast hordes of loitering, international press will swarm on the couple's chosen hospital and take over the designated press pen. Think, Olympic-level jostling.

Usually, within hours, the couple's press office will put out a terse press release saying the Duchess has gone into labour, offering an infuriating dearth of actual information, details or clues. The world makes a cuppa and settles in for a wait.

Twitter goes into meltdown. Nervous editors the world over try to publish stories about the royal birth but have essentially no facts and are just guessing. All drink seventh cup of coffee.

QUICK, GET HER MAJ ON THE BLOWER

The baby arrives! The first thing new Dad Prince Harry will do is to pick up an encrypted phone and call Buckingham Palace to inform the Queen. The next calls will most likely be to Doria Ragland, Meghan's mother, and Prince Charles.

MORE PAPER

Another press release! But this time, some actual hard facts. It is most likely we will be told the bub's sex, weight and time of birth. According to Gert's Royals, a blog that boasts an encyclopaedic knowledge of all things royal, if the birth happens during the night, the Palace will wait until about 8am to put out the press release.

GET OUT THE EASEL JENKINS

Soon after the official announcement, Buckingham Palace will dust off the gilt-framed easel and plonk it near the front of the Palace gates where it stays for a day with the official announcement. (After that the piece of paper in question is saved for posterity.)

THIS IS WHERE THINGS GET COMPLICATED

With all three of her births, Kate was out within a matter of hours, holding her baby and looking ridiculously immaculate. There is every chance Meghan will eschew the need to look elegantly coiffured so soon after labour, so it is possible she will spend a day or more quietly in hospital.

LET'S TALK GRANDPARENTS

According to reports, Doria will be arriving in the UK at some stage in the next month, so expect to see her popping in and out of the hospital. It is most likely the Prince of Wales will meet his fourth grandchild behind closed doors and within easy reach of a fortifying gin and tonic should the infant start to cry.

WHAT'S IN A NAME?

Meghan and Harry's media apparatus will put out a press release revealing the newest Windsor's name. We can expect this anywhere from two to 10 days after the bub's arrival.

OK BUT WHEN WILL WE SEE THE BABY?

Good question. Again, while Kate preferred to introduce her tot to the world's press within hours of it emerging from the womb, it would not be outrageous to think Meghan might do things differently. This could mean an appearance in front of a small contingent of photographers within the first week, or the couple might just release an image of the fuzzy newborn and forgo facing the media gauntlet. Doria is probably pretty handy with an iPhone.

THEN THINGS WILL GET EXCITING IN JUNE

June 8 is the Trooping of the Colour, so Meghan might (as Kate has done previously) briefly return from maternity leave to make an appearance on the Buckingham Palace balcony. Or she might stay at home with her feet up, enjoying some blissful peace and quiet while the baby snoozes.

The other thing that will happen in June, or maybe July, is the christening. On the day, a press release will be put out naming the godparents (Hi George! Hi Amal!) and we, the ever-patient public, will get another lovely glimpse of the Sussex bub.