At 2.5 weeks you can feed the puppies every 4 hours with 6 hours between feeds at night. Ensure that when you make your puppy formula use it within 24 hours and keep it refrigerated. Be very hygienic with the puppy bottles etc. Puppy milk is still to be served at 98 degrees Fahrenheit. Burp the pup during and after the feed by patting the pups back gently over your shoulder.
Don't feed a puppy on their back. A one week old puppy needs 13ml of milk per 100g of body weight. A 2 week needs 17ml per 100g of body weight. A 3 week needs 20ml per 100g of body weight. At 4 weeks needs 22ml per 100g of body weight. The puppies will need to be stimulated to pee and poop until they are 21 days old. You do this by gently massaging the puppies belly and genital area with warm moist cotton wool. Before and after feed. At 3 weeks pup should be able to eliminate on its own.
When the Pups are 3 weeks you can start to introduce puppy mush. You will continue bottle feeding the puppies also. Give them some puppy mush 3 times a day. Buy high quality premium puppy nuts. Soak the nuts in some water or milk replacer. One part nuts to 2 parts liquid is best. In your blender blend up the puppy nuts and add some puppy milk replacer. Make sure that the puppy mush is not too thick should be like watery porridge. Use a flat pan to serve the puppy mush to the pups. Pups will make a mess and get more of the food on themselves than in their mouths at first but they figure it out fairly quickly. I'd serve it warm also. Also provide a shallow water bowl. The pups should lap it up but don't overfeed.
The pups will still need to have their temperature regulated at this stage. You can use a heat lamp, heat pads or hot water bottles. Remember the pups cannot regulate their temperature yet. During the second week 85 degree Fahrenheit, during third week 80 degrees Fahrenheit. At week 5 the pups can be kept at room temperature 70 degrees Fahrenheit. If the pups are lying beside each other they are at a happy temperature but if they are lying on top of each other and crying they are cold. Weigh the pups once a day. Loss of weight is a sign that there is a health problem.