Which time? Seems they keep coming back! Youngest graduated from college 4 years ago, lived home for another year, then went to grad school. So, officially, that was when I was 59, DH was 60. My son keeps coming 'home', though. and he just turned 40. We keep hoping that the last time was really the last time!
I enjoy my time, but make sure I have kids in my life and home for vacations and fun.