Little dogs, such as chis, you can usually expect that they will achieve most of their growth in the first 5 months-they usually reach their adult size by 6 months, but then they will start to fill out. With very slight increase in heighth. Usually by a year they have reached their max. If you are breeding, then you want to wait until the third heat cycle to breed-close to two years before their first litter.
So, by the weight chart-you will probably see an adult close to 5-5.5lbs