The owner of the Tampa Bay Bucaneers American football team had hoped to get his 800 million pound ($1.54 billion) revised business plan to United's board by the end of this week.
"There are still quite a few things to set in place," one person close to the process said on Friday.
Glazer still needs to meet with financial backers to finalise the debt package he will need to buy the world's richest soccer club.
"We're just going through the process of talking to the credit committees and getting them to agree," the source added.
United's board has rejected two earlier bids from Glazer to buy the 15-times English league soccer champions.
