By law in the UK, all dogs over 8 weeks old must be microchipped prior to rehoming and registered on an approved database.
I understand
Kennel Club(KC) registration means that the advertiser/breeder completes a KC registration form and receives from the KC an Owner Registration Certificate for a puppy. There is no time limit.
However we advise that the breeder registers all the puppies in the litter at the same time at approximately 4 weeks of age.
This means that the documents can be received in time to pass them to the new owner, so they can then complete change of registered ownership.