The couple, who got married in Italy in 2013, recently put their one-bedroom condo in Nolita, Manhattan on the market and pals say they are keen to upgrade before the model gets pregnant with their first child.
A source said: ''Chrissy has been hesitant because of her busy modelling career, but she's finally ready. She's been getting advice from her friends with kids.''
The 'All of Me' hitmaker has no doubt his wife will be a great mother.
The insider added to Life & Style magazine: ''She's so good with their three dogs.''
The Sports Illustrated beauty, 29, recently admitted she wants to have a very large family.
She said: ''We want a lot of kids. I would love to have three or four of my own, and then adopt a few. So basically I'll be pregnant the rest of my life.''
John, 36, doesn't really care whether they have sons or daughters, but admitted: ''[Chrissy] thinks I'm not athletic enough to have a boy. I'm a musician, I'm good with women, and I'm a feminist, so I think I'll be a good 'girl daddy.' ''