cronehood
n. The stage in a woman's life after her children have left home.
Examples
1997
In a society obsessed with youth, older women are challenging perceptions about age and femininity. Across Canada, in small groups and at large gatherings, they are celebrating their accumulated years and grey hairs. To mark the rite of passage, they have appropriated the old English word "crone" and reinvested it with a more positive meaning.

Cronehood is the third stage of womanhood, after youth and motherhood, explained Betty Nickerson, an author and founder of Amazing Greys, an annual retreat in British Columbia for crones and crones in training.
—Lila Sarick, “Women embracing cronehood,” The Globe and Mail, October 21, 1997
1996
OK, baby boomers. Here's what the prudence police think you ought to be buying next. Long-term-care (LTC) insurance, to cradle your weary bones when you're 85. Prepare early for cronehood!
—Jane Bryant Quinn, “Aging: The endgame,” Newsweek, September 30, 1996
1972 (earliest)
…a perpetual turnover of women leaving to marry, have babies, or enter premature cronehood, but replacements were always waiting in the wings: in 1955, some 20000 women applied for 347 available posts at American.
—Ms. Magazine, May 1, May 01, 1972