
Weaning, for us, usually started by the end of week 3 going into week 4 and depending on how well the litter was doing. We started using warmed goats milk and teaching each individual puppy how to lap. Some were better at this than others...... and at this point most of their nourishment was still being taken from mum. We did this 4 times a day and once a day (NOT MORE) a tiny amount of lean raw mince (hamburger) - only once although the way this disappeared would tempt us to give more, which would upset their immature digestive system, so don't.
Once they could lap, then we added a good quality puppy food, complete food, and mixing it either with warmed goats milk, or warmed water into a porridge, cutting back on the moisture as they got older. Fresh water would be available, in a shallow dish from this point, but not overnight. With our big boned breed we'd also add scrambled egg, cottage cheese, and raw mince (not all at the same meal!!) and continue with the goats milk drink, but with a tiny breed, this isn't needed.
By just over 4 weeks, your puppies should be able to cope with the porridge mix. Yes, remove mum while you start feeding them but she should be let back in to clean up afterwards and to allow 'comfort suckling'. I did this up to around 6 weeks of age by which time our dams were off their litters, usually. None of our puppies went home before 8 weeks, and only then if I knew the people well and they were experienced. Otherwise we kept them to age 10 weeks.
For us, there was no hard and fast rule re weaning - when they are ready, they'll take to solids. Can't comment on the weights, sorry.