
I'd simply have the pups on solids by now.
Any pups that are slow at gaining or the rate of gain is flattening out would mean I'd start introducing puppy food mixed with puppy milk to a porridge.
I have started pups as early as the eyes are open at around 12 days.
In the normal run of things I offer my pups their first taste of puppy mush at 18 days, offer it twice next day so by three weeks they are on whatever amount they will eat 4 times a day.
If Mum is doing them well then the amount they eat is small, but as son as they need more they eat more and I always make up a bit more than they will eat, and Mum finished up, and at the same time Pups get a top up from the milkbar.