Dear Mr Mishra,
Normally you should not adopt a puppy less than 60 days as puppy needs to stay with its mom for breast feeding which is the most important starter for a puppy and gives immunity to the puppy. In USA its illegal to sell a puppy less than 60 days old but here in India as soon as the puppy opens its eyes breaders separate puppies from their moms and sell them as low as 25 to 30 days old. Neways now that you have taken the puppy, firstly get it checked by a vet for any existing diseases and get it dewormed. Now coming to your questions, first of all you need to feed the puppy minimum 4 max 6 times a day till he is 3 months old, there on 3 to 4 times a day till the puppy is 6 months old, there on twice a day, but keep in mind the Quantity as it should be fixed and divided into the no of meals. You may check the Dog food feeding label for the quantity required, as far as i believe for a lab puppy it should be between 400 to 600 grams a day depending upon the amount of exercise. Right now you should feed 2 meals of cerelac and 2 meals of dog food starter. You can order Dog food Starter from Dogspot if its not available in your town, here are the links:
You may choose any one if the above. You may stop feeding cerelac and gradually move to dog food starter as soon as you receive it. As far as Brands of Food is Concerned, there are lot of premium brands in the world but it all depends upon the availability that you get, however from Dogspot you may order as they do free delivery. Feed a starter till three months then you may shift to Royal Canin Lab Juniour available in 3kg and 12kg tailor made for Labrador Retrievers.
Feeding times should be depend upon no of feeds for 4 feeds it should vary between 4 to 6 hours of difference between meals. you need not feed the puppy midnight, just start the day early say 6 to 7 am first meal and last meal latest by 10 pm. Puppies do tend to get up in night to pee as they have a very small bladder but u need not worry to feed it midnight. Make him realize that he need to wait for the food, as the night time shall be the longest time difference between meals, it will adjust accordingly.
So order the puppy starter as soon as possible and till the time you get the starter you may try feeding him boiled eggs and boiled chicken without bones. Good Luck !!