At 19 months. It was 2 months after I stopped pumping at work (I work full time, gone about 10-11 hours 4 days a week). He was still nursing at night when it came back. I went back to exactly the same cycles as pre-baby.
I wish it had stayed away longer because now I get a lot of nipple soreness and I'm very irritated with nursing about 4-5 days around ovulation.