The countdown has begun for Royal Baby No. 2!

Prince William has reportedly returned to Kensington Palace to be by Kate Middleton's side after completing the first phase of his air ambulance helicopter pilot training in Norfolk, England ahead of the birth of their second child.

kate middleton family

Kate, William and George in April 2014.

Before going on early paternity leave, William, 32, originally planned to stay at the royal family's Amner Hall country residence — a two-hour drive from London — in the weeks leading up to the new baby's birth.

Related: Kate Middleton Breaks Royal Tradition to Have Mom Carole Help With Baby No. 2

But since he finished his training ahead of schedule, the Duke of Cambridge is now able to spend more time with his pregnant wife, 33, and their son, Prince George, 21 months, before they become a family-of-four!

kate middleton, prince william, prince harry

Kate, William and Harry in March 2014.

A spokesperson for Kensington Palace additionally revealed Prince Harry, 30, is also en route to London from Australia, where he is serving a temporary military term with the Australian Defense Force.

"Prince Harry will briefly return to the UK this weekend following the Gallipoli commemorations in Turkey, to attend the London Marathon as Patron of the London Marathon Charitable Trust," a palace source told 'Us Weekly.'