30 day puppy still has to be eating/drinking puppy replacer milk as its main diet (available at pet stores), but after around 10 days, you can introduce puppy canned food and soon after, dry food.
35 days is a fairly little time to offer them solid food.
I recommend giving your puppy cerelac.
You can feed them the baby formula we use.
After the 60th or 70th day, gradually introduce food into their diet while maintaining the cerelac, until your pet shifts to his or her main food.