Birth: Baby can perceive speech, cry, make some response to sound.
1.5-3 months: Coos and laughs.
3 months: Plays with speech sounds
5-6 months: Makes consonants sounds, trying to match what she or he hears
6-10 months: Babbles in strings of consonants and vowels.
8-10 months: begins to understand words (usually no and bay's own name): imitates sounds.
9 months: Uses guesters to communicate and play guesture games
10 months: Loses ability to discriminate sounds not in own launguage
10-14 months: Says first word (usual label for something) imitates sounds
13 months: understands symbolic function of naming
14 months: uses symbolic guesturing
16-24 months: Learns many new words, expanding volcabulary rapidly, going from about 50 words up to 400; uses verbs and ajectives,; speaks two word sentences.
18-24 months: says first sentence
20 months: uses fewer guestures, names more things
24 months: Uses many 2-word phrases, no longer babbles, wants to talk
30 months: Learns new words almost every day; speaks in combination of 3 or more words; understands very well; makes many grammatical mistakes
36 months: Says up tp 1000 words, 80% intelligible; makes few mistakes in syntax; grammar is close to informal adult speech.

Source: Bates O'Connell & Shore, 1987