When Meghan Markle gives birth to her royal baby, the Queen will be the first person to be told.
Royal protocol means she has to be the first to know when a new family member arrives, so Prince Harry will be making a very important call after meeting his son or daughter.
But Baby Sussex might get to meet his or her great-granny in the first few days of her life - and it's all because of some very good timing.
The Queen is staying at Windsor Castle at the moment, just as she does every Easter, so she's just up the road from Meghan and Harry's house Frogmore Cottage .
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She's had a number of engagements and events in the past few weeks, but they've all been very close to the home.
There are a few things in the royal diary for the next couple of days which are all within the castle walls.
On Friday she'll present at a Service of the Royal Victorian Order at St. George's Chapel. Once the formalities are over she will host a reception for everyone.
On the 7th she's hosting a luncheon for members of the Order of Merit, and she's holding a garden party on the 15th.
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She'll be back in London on May 20 for the Chelsea Flower Show followed by a visit to Westminster on the 22.
Her last few engagements have also been in Windsor, enabling her to have a long break away from London.
On Easter Sunday, which was also her 93rd birthday, the Queen was joined by members of her family for a traditional church service at St George's Chapel.
She beamed as she stepped out of the car to be greeted by the Duke and Duchess of Cambridge, Prince Harry, Princess Beatrice and other members of the family.
Meghan's exact due date is not known, but she's expected to give birth any day now.
