And on Wednesday, the husband-and-wife-to-be threw a pre-wedding beach party for over 50 guests in Puglia, Italy.
According to the magazine, Biel was recently spotted at a bridal boutique in Paris.
Life & Style magazine also echoes that the pair, who have been dating since 2007, are revving up to trot down the aisle.
"The wedding was top-secret, hush-hush," a close friend of the couple reportedly told the mag. "Save-the-dates went out in the spring and little information was given. Guests were warned that any phones or cameras would be confiscated, so best to leave them at the hotel."
A source told The New York Post's Page Six that the lovebirds chose a town close to the city because the location "means a lot to both of them".
The source said: ''The wedding is happening outside of Naples in a tiny town this week. It is their favourite place, a location that is very special to them. There will be a few hundred guests, and the maid of honour will be Jessica's longtime best friend, Lindsay Ratowsky.
"Jessica's stylist, Estee Stanley, who is also Justin's partner in his home décor business HomeMint, has been helping to plan the wedding."
Wedding guests were required to sign confidentiality agreements, reports E! Online, and were given no details about where the ceremony will be taking place.
"They were told just to fly to Italy," adds an insider.
"Guests flew out on Monday and landed in Frankfurt with no further instructions," a source told Celebuzz. "Upon their arrival, they were all given itineraries and tickets to the south of Italy, where the wedding festivities will take place."
Timberlake celebrated his bachelor party with pals in both Las Vegas and Mexico in September, so reports of a wedding this weekend could be on the money.
While ceremony details are obviously guarded, Britain's The Sun claims that the former 'N Sync singer has a treat in store for his future bride.
The tab reports that Timberlake has been "secretly rehearsing" a wedding dance with his ushers and best man for Biel - to the tune of her favourite 'N Sync track, It's Gonna Be Me.
"Justin has been working on this for months. Jessica used to love the track growing up and he wants it as a special treat," says a source.
"It will be very much tongue-in-cheek. There will be loads of exaggerated boy band moves and poses. She's going to love it."
The singer-turned-actor spoke candidly about his fiancée during a press conference with the Hollywood Foreign Press earlier this month.
"She's a really, really, really special person," Timberlake told reporters. "Plus, she's really, really, hot!"
He added: "I think it's important to remember that you go into something like marriage knowing that you don't know very much about it at all. But I do look at the marriage of my mother and stepdad, and what makes it work for them is that it's a team effort."
"[Biel] is single-handedly the most important person my life," Timberlake told Vanity Fair in June 2011. "In my 30 years, she is the most special person, ok? I just don't want to say much more, because I have to protect things that are dear to me - for instance, her."
Biel recently claimed to have little plans in place for the wedding.
"I've done almost nothing! I'm just enjoying being engaged. I do feel like there is a lot of time and nothing needs to be rushed. Everyone tells me that being engaged is the really special moment," she told the Chicago-Sun Times in August.
"Not that it gets bad when you get married. But being engaged is just absolutely amazing. You're in this romantic, ahhhhhh, breathless moment that I'm just trying to extend as long as possible."
Reps for Biel and Timberlake have not responded to the wedding reports.
Stay tuned for updates...
FAST GOSSIP
And finally...
* Ashton Kutcher rules as highest-paid actor on television.
* Shannen Doherty shoots down baby-bump rumours.
* Anne Hathaway to donate wedding picture proceeds to marriage equality.
* Uma Thurman reveals baby's name. Are you ready?
* Mel Gibson dating Hollywood stuntwoman Ashley Cusato.
* "I think it's going to happen one way or another" - Kylie Minogue musical still a go.
* Dancer denies splitting up Russell Crowe's marriage (+video).
* Megan Fox and Brian Austin Green welcome baby boy. She's been keeping it a secret for weeks!
* Kellan Lutz thinks he will win an Oscar.
* Katy Perry, John Mayer back on. Not that they were ever really off.
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