It doesn't matter if your ex hasn't started taking benefits yet, according to the Social Security website. You can collect Social Security benefits even if your ex hasn't started yet as long as you have been divorced at least two years.
Charlene Thompson, of Austin, Texas (not her real name), found that it wasn't easy to get her local Social Security office to recognize this. She went back to the office three times, asking if she could start taking early benefits at age 62 on the basis of her ex's contributions. They had been married 34 years. Each time, they said no. Charlene's benefits based on her own contributions were far lower.
Fortunately, a woman working for Seniors First encouraged Charlene to try again. This time, she talked to someone at the Social Security office who said, "Absolutely!" and sent her the proper forms.