My oldest, at 18 months. My youngest, at around 30 months. There is a lot of variation.
There are many elements of speech and language. In my opionon, the most important thing is that your child understands you and can follow simple instructions. Beyond comprehension, are vocabulary which can be slow to develop in some kids and articulation which can be even slower. My 3 year old (the younger) just had a speech evaluation. She has the comprehension and vocab of a 6 year old, but her articulation is at the 35th percentile for her age. But she is improving a lot every day.
So you need to ask
-does he understand me?
-is her understandable by others?
-is he stagnating or improving?
Odds are he is fine. One thing to keep in mind is that the standards for government services in this country are pitifully low, like the 25th percentile for age. So, you need to decide what your personal standards are and your point of willingness to seek therapy. My child's teachers have always said, the key for them, is whether the speech production is interfering in their social development. So, one more question is
- do his peers and teachers understand him?
- is he embarrassed by his speech or unwilling to talk?