Los Angeles: "A Team" star Jessica Biel and singer-actor Justin Timberlake are not holding back on the celebrations when they tying the knot this coming August.

Though 30-year-old Biel and Timberlake, 31, are known as a notoriously private couple, they are planning to have big fat wedding, reported a magazine.

"They have lots of people they want to invite. They remain undecided on the venue since they will need a place that offers plenty of room," a source said.

As for her wedding planning, Biel is said to have got a helping hand from Timberlake's mother, Lynn Harless, who is helping her with every little thing.

The actress still has designer Monique Lhuillier as her first choice when it comes to her wedding dress.

The couple got engaged in December last year while they were up in the mountains of Jackson, Wyoming. Days later, Timberlake's grandmother confirmed the engagement rumors, clarifying that the proposal was actually done in Montana.