zoey's breeder told me 18 months and that is what all the charts i have found state. though most of the chi owners i have met told me they stop at approx 6 months and just fill out a little from there.
Man, I hope Hershey is almost done growing. He is 7 months old today and he is already nearing 9 lbs. He is not fatty really but tall and muscular. He will eat constantly and wants stuff all the time though, so I am sure gonna have to keep an eye on him.