This morning we had mini-pancakes for breakfast. I gave my youngest son (who is two) three mini-pancakes. When he was still hungry, I gave him two more.
Half-way through his final pancake, he said:
There is interesting research that suggests, through an ingenious experiment, that we are literally born with some knowledge of numbers. Not symbols, like the word “five” my son is using above, but numbers. It seems to me that while my son is developing his language, it is an excellent time to develop his innate understanding of number and connect it to the language he is learning.
So I pay attention to what my son says and even at two years old, when he is first developing language, we count together, we group objects when we play, and I help him give language to the thoughts he is already having.
Math Thinking 
Follow up:
My son consistently, when counting down to blast-off his rocket, counts five, four, three, one, blast-off! I think Timon used five here to mean big number, rather than actually the number of pancakes he ate, if that makes sense.
He clearly does not have a one to one correspondence between the number words and numbers of objects themselves.