It was recently announced that on June 14 the Duchess of Sussex will accompany Her Majesty on an official visit to Cheshire, England, HRH's first big event without Prince Harry by her side.
Hold your horses, Jump-to-Conclusions club. Not only are there explanations for the invitation delay (if you even want to call it that), but there is also proof that Queen and Catherine undertook an engagement prior to the date in question.
For instance, following her North American tour, Catherine accompanied the Queen to preview an exhibit at Buckingham Palace. That year the exhibit featured Catherine's Sarah Burton for Alexander McQueen wedding dress.
William was not present, and though the engagement didn't require the women to travel by train, plane or automobile, it was still the Queen and the Duchess of Cambridge. Just the two of them. With photographers.
It's also important to reiterate that Catherine and William undertook a nine-day tour of Canada and Southern California just two months after their wedding. Finding time to accompany the Queen somewhere would have been nearly impossible, given that Her Majesty was due to attend the Trooping the Colour and Order of the Garter Service, two big events in the royal calendar.
Furthermore, it was widely reported that the Queen granted the couple a two-year "grace period" to enjoy life as newlyweds; William was based in Anglesey, Wales as a search-and-rescue pilot with the Royal Air Force, and it was important to him that he and Catherine live as normal a life as possible before becoming full-time working royals.
At the beginning of 2012, William was deployed to the Falkland Islands for six weeks. The Queen took this opportunity to bring Catherine along on two visits; one to famed food emporium Fortnum & Mason in London, and a Diamond Jubilee event in Leicester.
In the latter city, Catherine told well-wishers that she was being "well looked-after" while William was away.
One other thing to keep in mind is that Catherine was very new to royal life, despite dating William for the better part of a decade. William took great pains to make sure that she was as protected and prepared as possible for the onslaught of publicity her position as his wife would bring. After failing to ensure that the late Princess of Wales adjusted properly to being a royal, the Queen and Prince Charles were willing to give Catherine the space and resources she needed.
Meghan, on the other hand, is an actress by trade, meaning that she is used to handling publicity and living in the spotlight.
These qualifications however, don't mean that she was better suited to accompany the Queen sooner than Catherine did. If anything, Catherine paved the royal way for Meghan, making it easier for the palace to determine what she'd be able to handle.
So there.