Benefits of peach and nectarine 

The only difference between peach and nectarine is the peach fuzz... And of course there is the size of the nectarine, which is smaller compared to peach, whereas its aroma is very strong.  So everything we mention about peach is true for nectarine.
Most doctors recommend introducing peaches to babies at 4 to 6 months. Especially for babies that started eating solids before month 6, peach is a very good food source...It is sweet and delicious.
You can give it to your baby with chicken, banana and even avocado or mix it with yoghurt. Also if your baby is ready to eat  finger foods you can slice it and give it to them. Most of the time it is better to peel of the rind. If it is slightly slippery, maybe you can sprinkle some  wheat germ on it.
Keep in mind

You can give your baby peaches when he is suffering from  constipation. Its fiber content will help him to overcome constipation.
It is not very good to cook peaches. All the nutrients in it are lost when cooked. Try to give peaches to your baby without any processing.
Pesticide is used when producing peaches. It is good to act cautious.

Peach is diuretic. To prevent further dehydration, you should avoid giving peaches to your baby when he has diarrhea.
Click here for methods to overcome diarrhea:
Nutritional value per 1 medium sized peach;

Vitamin A 524 IU
Vitamin C 19 mg
Potassium 193 mg
Phosphor 12 mg
Magnesium 6.9 mg
Calcium 5 mg