She went home to Mississippi after Thursday's program to be with her ailing mother, Lucimarian Roberts.
Roberts is still scheduled to begin her final preps for her bone marrow transplant next week.
Her last day before leave was originally going to be Friday.
On Monday's edition of the ABC News wakeup program, Roberts had announced the original start date for what's being called her "extended medical leave."
Roberts told viewers in July that she has MDS, a blood and bone marrow disease once known as preleukemia.
But looking further ahead, Roberts noted she is luckier than many workers who become ill. She says her bosses have been generous in giving her the needed time off, and her job is waiting for her when she's well enough to return. She described herself as "very blessed."
The Associated Press contributed to this report.
