Perhaps one of the biggest disparities for a baby's physical development is walking. You've probably heard of some babies walking at 6 months, which is a rather incredible feat. Then there are babies that don't walk until 15 months. That is a 9 month difference. But the majority of babies will start actually walking between 12 and 14 months.
Out of five children, I only had one early walker, at 9 months. Three of my children started walking right at 12 months and then I had one late walker at 14 months. The child that didn't walk until 14 months probably could have walked much sooner, but he was a very cautious baby and when he started he really rarely fell down.
Truthfully, one a child is mobile there is no stopping them, so a late walker is probably easier on the parents. But as far as development, anytime within this range, 6 to 15 months, is no cause for concern.
