Friends claim Aniston has invited her former mother-in-law, Brad Pitt's mum Jane, to the nuptials and Vaughn is going to great lengths to shape-up for the big day.

A Pitt family source tells Life & Style that Aniston has told her former sister-in-law Julie, who has also been invited to the wedding, that although a date has not been set, the actress would like it "sooner rather than later".

Vaughn reportedly went down on one knee while the couple were in Europe promoting the film that brought them together, The Break Up.

And Life & Style reports that Vaughn is so serious about looking his best when he weds Aniston, he has started the Zone diet, which Aniston has been a long-time fan of.

According to the publication, Aniston told a friend, "He's started the Zone diet, and he's working out. He looks great."

Aniston is reportedly waiting for the fuss about her ex-husband's new baby with Angelina Jolie to die down before exchanging vows with her reported new fiance.

But an insider insists Aniston is getting serious about her wedding plans: "Jen's already asked Courtney Cox to be her matron of honour."