The diagram shows typical eruption patterns for children. (Click on the diagram to enlarge it.)
As you can see, from the diagram, the upper central incisor should start to show between 8 and 12 months. The tooth should them be replaced with an adult tooth in the 6th or 7th year.
The first teeth to erupt are typically the lower incisors at 6- 10 months. Parents should watch for these teeth. When they erupt, it is time for their first check up. If, these teeth do not erupt after 12 months, you should call your dentist to discus the situation.