Los Angeles: Hollywood couple Justin Timberlake and Jessica Biel, who got engaged recently, are planning to tie the knot soon and are deciding on the dress and venue.

After nearly five on-and-off years together, the twosome, who got engaged in December, will marry this summer, reported Us magazine.

"The big day's this summer at a private estate," an insider says of Timberlake, 31, who proposed to the actress, 31, in late December.

And the actress is picking up a Monique Lhullier number for D-day.

"Monique Lhullier is her No 1 choice for the dress," the source revealed of the designer, whose dresses have been worn by such A-list brides as Reese Witherspoon, Jessica Alba, Vanessa Minnillo and Shannen Doherty.

The couple have been quite private about their relationship. It took Biel about six weeks to debut her engagement ring; she finally sported the rock at a Saturday Night Live afterparty on February 18.

"It wasn't huge. It looked vintage and might have been custom made," said a witness.