It takes several weeks if the limb is properly stabilized and immobilized. If it's not then it could be reinjured and/or not heal correctly. I would suggest having your rabbit seen by an experienced rabbit vet to have the break splinted properly. https://rabbit.org/vet-listings/
I agree, you need to see a vet, because they will need to X-ray to check the bones are properly aligned to ensure they heal back in the correct position.