Simpson and Johnson, who got engaged in 2010, delayed their wedding plan after she got pregnant, reported Ace Showbiz.
"Jessica wants it to be the hugest, grandest event of the year. She's calling it a 'supersize wedding'. The venue is the perfect setting," a source said.
Simpson, who has two children Maxwell and Ace with the former NFL star, previously was married to Nick Lachey. She wore a traditional white dress for the previous wedding, but she reportedly is going to wear a pale pink custom-made Marchesa gown for this one.
Despite the wedding preparations, Simpson apparently is still busy with work. On June 27, she took to Twitter to share an ad of her titular perfume. In the promotional photo, the 33-year-old star looked beautiful in a nude-coloured Oscar de la Renta gown which is featured with jewels and feathers.