Prince Harry and Meghan plan to move out of Kensington Palace in March - at least a month before their baby is due.
The couple are currently overseeing renovations at their new home at Frogmore Cottage near Windsor Castle.
The move out of London was announced by royal officials at Kensington Palace at the end of last year, but they did not give a timescale for the move.
ITV News has been told the Duke and Duchess of Sussex have pencilled in a moving date of March so they can get settled into their new home several weeks before Meghan has their first child.
The Duchess recently told crowds on Merseyside that that their baby was due in "April or May".
The couple have been living in Nottingham Cottage within the grounds of Kensington Palace since they got married - but it’s thought they want more privacy for their new family as well as more space.
The relocation announcement sparked dozens of stories that Harry and Meghan wanted to move away from William and Kate because the two couples have not been getting on.
But a need for more breathing room between the two brothers - rather than the two wives - is thought to be closer to the truth.
William and Harry have worked together and lived together for a number of years but Harry now wants the space to be able to focus on his own wife and child.
There are also more bedrooms at Frogmore Cottage so Meghan’s mother, Doria Ragland, can stay with her daughter and son-in-law when she becomes a granny.
Windsor means a lot to the couple as they chose St Georges Chapel in the Berkshire town for their wedding last May.
They also chose the grounds of Frogmore Estate for the evening reception.
Kensington Palace has never commented on speculation that the Duchesses of Sussex and Cambridge do not have a close relationship - although, earlier this week, royal sources did confirm they are monitoring the worst cases of online abuse centered around the many stories about the two women.
The Duke and Duchess of Sussex’s move to Windsor also means they may have to chose a different hospital for the birth.
William and Kate had their three children, George, Charlotte and Louis, at the private Lindo Wing of St Mary’s Hospital in London.
Frimley Park Hospital in Surrey is closer to Windsor and it’s also where Harry’s Aunt Sophie, the Countess of Wessex, had both of her children, Lady Louise Windsor and James, Viscount Severn.
The Countess opened a neo-natal unit at the NHS hospital in 2014.