As far Ayurvedic Pediatrician
I am not recommended artificial food like nan 1 , Zerolac etc
my opinion is Breast feeding is best feeding for baby.
If due to any reason Breast feed in not available. Then you can start Buffalo milk (Star with 1 part of milk and 1 part of water, then gradually decrease water quantity )
For 6 month child you can start:
Biscuits in milk
Any cereal may be mixed with water or milk.
Sometimes its very difficult to accept new food, so at time try one type of food for several days.
"i wish your child good health"