My ds6 did not start speaking well until he was about 4. However when he did he started speaking in full sentences. He had trouble pronouncing certain words but his vocabulary in certain interest areas has always been above average. He was identified as gifted in the first grade. DD8 started speaking very early. She was singing the alphabet song at 18 months old and could speak in full sentences before she was three. She has not however been formally identified for the gifted program.