AP

Prince William stepped out this week in his first official royal engagement since becoming a dad and now we know when his wife, Kate, will make her first official appearance.

The Duchess of Cambridge, 31, will attend a charity dinner with Prince William on Sept. 12, less than two months after she gave birth to the couple's first child, Prince George, according to palace officials.

The couple's united return to the public spotlight comes on behalf of a cause near and dear to William's heart, Tusk Trust, a British charity that funds conservation projects in Africa. The duo will attend an awards dinner to benefit the charity.

Photos of Radiant Kate Showing Off Royal Baby Boy

The last time Kate and William were seen together was in the days just after their son's birth. The couple appeared with their newborn, His Royal Highness Prince George Alexander Louis of Cambridge, outside of St. Mary's Hospital in London on July 23, the day after his birth, as they departed home for Kensington Palace.

They were seen leaving the palace not long after arriving home, reportedly to head to Kate's parents' home in Bucklebury.

O n Wednesday Prince William made his first official royal appearance since becoming a dad at a fair in the couple's second home, Anglesey, where he revealed a few details about their young son, the third in line to the British throne.

What Does the Prince's Name Mean?

"He's pretty loud but of course very good looking!," William said, while also attending a fellow fair-goer that little George is not yet sleeping through the night.

Now all eyes will be on Kate's first appearance back and, no doubt, what she wears, how she looks and how see seems to be handling motherhood.

The duchess was lauded for donning a blue polka dot Jenny Packham dress that did not hide her post-birth "mummy tummy" as she left the hospital the day after giving birth.

Prince William, Kate Register George's Birth

"I think what Kate has done for new moms has really given them a tremendous gift," thebump.com editor Lori Richmond told ABC News at the time.

Tell us what you think. What designer or look do you think Kate will wear in her first royal appearance after baby?