Language development in children occur according the following schedule approximately:
Language development at 6 Months:
Vocalization with intonation
Responds to human voices without visual cues by turning his head and eyes
Language development at 12 Months:
Uses one or more words with meaning
Understands simple instructions
Language development at 18 Months:
Has vocabulary of approximately 5-20 words
Language development at 2 years:
Can name a number of objects common to his surroundings
Approximately 2/3 of what child says should be intelligible
Vocabulary of approximately 150-300 words
My and mine are beginning to emerge
Language development at 3 years:
Knows chief parts of body and should be able to indicate these if not name
Handles three word sentences easily
Vocabulary of approximately 900-1000 words
About 90% of what child says should be intelligible