On average, it's about two years from the time a girl first starts to show any breast development to the time that she actually starts her periods. Since girls in the United States start their periods anywhere from 9 to 15 years of age, breast development starting as early as 7 years of age is normal. In general, a girl starts her period in a pattern similar to her mother; if Mom started early, her daughter is more likely to start early. This isn't an absolute rule, though. Factors such as nutrition overweight children can start sooner than they otherwise might, and underweight children may start later and illness can influence the onset of puberty. Keep in mind that, when you discuss body changes and puberty with young girls, your approach may need to be very different if you're talking to an 8-year-old rather than a year-old.
I am a somewhat recently single single mother. I have been dating a man for the past 6 month who I knew growing up. We have already introduced our kids as they are older and we didn't feel we needed to wait an extended period of time. My kids are girls ages 15 and 12 and his is a girl age
Is this normal? There's a wide range considered "normal" regarding when puberty starts and how fast it progresses. For girls, puberty generally starts sometime between 8 and 13 years of age. For most girls, the first evidence of puberty is breast development, but for others it may be the growth of pubic hair.