I would give it time, especially if the child naps well (that is the most important thing!). I have one like this who is now 14 months and way behind the other two who are close to his age, but I just keep giving him every opportunity to strengthen his legs (no exersaucers, etc) and try to enourage him to do things by himself (finger foods, drinking from a cup etc) and he is improving. He is a sweet little guy and easy going, so for me, it is worth the extra physical work of helping him do things. For me, the investment into a young one is better in the long run, but only you know what you can handle depending on the other kids in your care. Every child develops at a different rate.