The couple got engaged last week and Bleakley later claimed to be "beyond shocked" by the proposal.
"Frank has told Christine she'll be an honest woman before her 33rd birthday in February," a source told Heat.
"And she wants a baby sooner rather than later. Christine has always told Frank that she wants a baby before the age of 35. So he's had this in the forefront of his mind - they're not wasting any time."
Lampard has two daughters with his former partner Elen Rivas and the girls are reportedly to serve as flower girls at the ceremony.
Rivas has said that Lampard's love-life is none of her concern, adding: "I haven't spoken to him about the engagement and I don't want to. I don't care. I still talk to Frank, but I have no feelings for him - that was all a long time ago."
Lampard and Bleakley are said to want to avoid a "tacky celebrity wedding" and will shun numerous offers of magazine deals.
> Peter Andre, Elen Rivas 'seen kissing at Amy Childs party'