The couple had been planning to tie the knot in May but after learning that Brad and Angelina Jolie were going to become husband and wife the same month Jennifer and Justin pushed their date to August to ensure their wedding wasn't overshadowed.
A source told the upcoming new issue of Us Weekly magazine: ''She does not want her day associated with them.''
At one point Jennifer - who split from Brad in 2005 - considered bringing her wedding day forward to avoid a clash but then came to the conclusion there was no need to rush her plans.
The source added: ''Justin got weirded out by all the rushing ... ''Nothing has happened on that front (wedding) in a month.''
Jennifer, 44, and Brad, 49, can't seem to escape each other. They even got engaged to their new partners within a few months of each other last summer.
The 'World War Z' star and Angelina, 37, are believed to be planning to marry at their Chateau Miraval estate in Provence, France, this month and Brad obtained a wedding licence at the end of February which allows him to wed within 90 days.
Last week, it was reported former 'Friends' star Jennifer would not be making Justin, 41, sign a prenuptial agreement to protect her estimated $150 million fortune.