The range for speech development is wide. Here is what is actually normal: 0-3 months: cooing. 4-6 months: babbling begins. 7-12 months: intentional babbling, may say 1-3 words by 12 months. 12-18 months: 3-20 words. 18-24 months: 50 or more words, starting to combine two words.
When to seek evaluation: No babbling by 12 months, no words by 16 months, no two-word phrases by 24 months, or loss of any language skills at any age.