The 44-year-old actress is due to wrap filming her latest project in Connecticut at the end of this week and her friends are expecting a wedding ceremony to follow shortly, reported Sun online.
Aniston has reportedly already picked out the couple's wedding bands, chosen a date and even a dress.
The details of the wedding has been kept under wraps in an attempt to keep the event a secret but some friend of Theroux's are tipping comedian, Ben Stiller, as a potential best man for the small and intimate wedding ceremony.
Even the guests won't know the venue until the last possible minute but sources close to the couple have claimed that they have looked at options in Hawaii.
"Jen is going to great lengths to keep the wedding details a secret so it does not become a huge media circus like her wedding to Brad. Just a few dozen of their closest family and friends will be there. But news is beginning to leak that the date is just a few weeks away now," a source said.