I put down 24+ months even though my daughter is only 19 months now, because we are still going strong with breastfeeding and I can't imagine weaning her soon.
I had always thought that I'd wean a child before she could talk to me about breastfeeding -- don't ask me why, it was an irrational thing -- but then along came my daughter and not only has breastfeeding been so good for her, but when she started talking about it, she named it "happy milkies". How on earth could I wean her, absent some pressing medical reason, when she curls up against me and asks for her happy milkies?