On Saturday night, she made a public appearance at the Invictus Games, joining Harry in Toronto (where she lives) at the Paralympic competition he founded three years ago.
She's already well acquainted with his circle of friends, and is said to have met the Queen.
The prince even released a statement, confirming they were a couple and asking the press to back off, a highly unusual step that suggested Meghan is no flash in the pan.
Other factors hint that the Los Angeles native is soon to have official status. She has stopped promotional work (though she does appear on the cover of Vanity Fair this month, having given them a carefully un-revelatory interview).
She has also turned down a contract to appear in the next series of Suits - the surprise hit legal drama which has made her acting career.
But perhaps the most significant clue lies in the fact that Meghan has given up the lease on her car in Canada, a mundane yet concrete piece of evidence supporting rumours she is planning to spend more time in Britain as of November.
So what can she expect of life over here, as a Royal other half? She has already been spotted shopping on High Street Kensington, which as the Duchess of Cambridge can attest, is a prerequisite.
But what other highs and lows lie ahead? Kate is currently elbow deep in childcare and has severe morning sickness, so will likely be too busy to dispense advice. But don't worry, Meghan, we're here to help.
Here's how to survive life in The Firm.
The clothes
Keep it simple. Nobody likes a show-off, and as the newest member of the Royal family, it's important not to upstage anyone further up the pecking order - like when Pippa's bottom became the talking point of William and Kate's wedding.
You don't want to become famous for your assets. Much better to establish a reputation as a fun and fabulous embellishment to Royal life - like Camilla, the Duchess of Cornwall - than as a pouting clothes horse (think Fergie circa 1985), or gap yah type (think Chelsy Davy's fondness for dangly earrings and heavy beaded necklaces). And beware the curse of Jigsaw. Dress too drab and you'll be branded boring (Kate, circa 2008).
Stick to a mix of designer British brands - Mulberry, Erdem, Preen and Hunter - and you should have all bases covered.
How to behave
Nothing diffuses tension so well as a big flash of teeth - one thing the wistful-looking Cressida Bonas never mastered. Chatting is also important: study the Queen's use of prosaic opening lines, and borrow some banter from William and Harry - though not Prince Philip.
Self-deprecation also goes down well, as does gentle teasing, and a thorough knowledge of a surprise niche subject, such as the B-roads of Gloucestershire, can be useful for small talk.
Always keep your knees close together when getting in and out of anything (cars, helicopters, nightclubs). Past Royal girlfriends, like Chelsy, have struggled to adjust to the attention that goes with being in a relationship with Prince Harry, but as a professional actress you will cope. It's like being on the red carpet every day, without the bother of having to make a film.
Meeting the family
You will already have been taught how to curtsy - one foot in front the other, a gentle bend of the knees.
Other useful tips would include not volunteering an opinion unless you're asked; feigning a love of corgis and dogs in general - which should be no problem, since you have two of your own; avoiding passing comment on other members of the family, at least until after you're married; and pretending you love very cold places like Scotland and Norfolk, which, having spent 7 years in Canada, you will have no problem in doing.
To get on the right side of Prince Charles, it would be wise to express an interest in architecture, botany, painting and Aston Martins.
A healthy appetite and thirst for heavy liquor will also stand you in good stead - nobody likes a clean-eating bore who doesn't appreciate a Dubonnet, or two.
Public appearances
This is a delicate line to tread - do too many and the other Royals will hate you for showing them up; too few and you will be labelled work shy. The trick is to take up patronage of as many charities as possible, that do something in which you're genuinely interested.
That way it won't seem quite so boring when you're faced with a dozen cold salmon lunches in one week. Keep careful tabs on your wardrobe to make sure you don't wear the same outfit too often, though it's important to show signs of thrift by reusing certain pieces in different combinations.
Choose your haircut wisely, as it will be closely scrutinised. A trim now and again if fine, but dramatic restyles should be once a year at most - these are a big deal for the tabloids, and tend to push all other news off the front page.
Where to shop
You may think Harrods. This is wrong. As a rule, stick to solid British brands, like John Lewis, Barbour, Land Rover, Dyson, as nobody will complain if you spend thousands there. Look out for Royal crests - any shop with one has been officially sanctioned, so you are free to spend a fortune on Prestat chocolates.
For groceries, Waitrose is a safe bet, especially if you buy anything from the Duchy Originals line (though make sure you tell Charles how much better their biscuits/marmalade/sausages were when he ran it).
Beware of going too high or low end - one of the nuances of our class system is that you get as much stick for shopping at Lidl as you would at Fortnum & Mason. The trick is to strike a balance between Scrooge and Marie Antoinette.
Where to live
This will be decided for you - Harry's current home is Nottingham Cottage, a detached two-bedroom house behind Kensington Palace.
You may find it quite poky compared to the Californian-style bungalow you currently call home, but it's very private and handy for Kensington shops, plus there's a new Mahiki nightclub opening at the end of your drive any minute.
There's also talk of Harry taking over Clarence House once Charles accedes to the throne, since he will be moving into Buckingham Palace, and William and Kate don't want to leave Kensington Palace.
That really would be a coup. Who knows, a four-storey John Nash mansion in the centre of London could make it all worth it.
