The first teeth show up, normally, a little over 6 months of age.
The first frontal teeth (Two above and two below) are the first to show up from 6 months of age.
When turning two and a half years, all the teeth and molars have erupted.
There are 20 milk teeth: 10 above on the maxilla and 10 below on the mandible.
Remember that the first definitive molars (permanents) come out behind the last milk molar tooth, around the 6 years of age.
Source: Healthy Child, Healthy Mouth.