
Nothing wrong with that as it's your puppy food of choice.
By the time mine are 4 weeks I do add other foods to one of their meals, like minced meat, tripe, Scrambled egg, etc, pretty much the extras Mum has been on.
This is primarily to get pups used to a variety of foodstuffs they may encounter once in their new homes, though you should give the new owners enough of the JWB puppy to last each of them a week or two so that pups don't experience a sudden change in food at such a vulnerable time as changing homes.
Pups will need to be on at least 4 meals a day plus feed from Mum as often as she wants. She should be allowed free access to them (apart from when you feed them, so she doesn't scoff their food), but should be able to get away from them too.