Screw an ITAP into the bone stub, reinforce it with some titanium
bands, take some drugs, and pet a kitty with your new cyborg arm.
Ah, cyborgs. Personally, I design the electronics (neurostimulators) for cyborgs (usually old people), but the mechanical stuff is pretty rad, so I follow it too.
There are some relatively recent advancements in prosthetics that you should be aware of, though it doesn't currently reduce healing time, I think this method would be the easiest to start with in order to accelerate healing time.
Intraosseous transcutaneous amputation prosthesis or ITAP. Translated to English that means, in-the-bone and through-the-skin limb replacement. The very cool thing about these prosthetics is that they attach directly in the bone and don't rest on a healed over stump. This means that loads experienced by your character, such as shoveling snow, can be taken through the skeleton rather than through soft tissue. The lost limb is better replaced because the user regains sensory signals to the bone; so called osseoperception. This reduces the learning time compared to normal prosthetics, because it's much more like the original limb.
The most famous patient, currently, for these special prosthetics is a cat named Oscar.
There are several human patients, and most of the photos for them are a bit more gruesome looking, so I won't add them here. But have yourself a google image search.
The main concern you'll have is allowing sufficient time for the bone to heal and hold onto the titanium bone implant. I think you can accelerate the bone healing with drugs and by reinforcing the bone with a custom boot or bands. There are a few examples of this with femur fractures or hip replacements, but typically medicine is not concerned with making someone better in three weeks, because we're still working on the getting better part. The best path for further research, since ITAP is still fairly new, is with osseointegrated titanium implants in general. Any advancements there will, for the most part, also apply to ITAP devices.
Once the bone part is taken care of the rest is not as much of a concern. The skin and other soft tissue around the titanium will not be load bearing, so it can take longer to heal. This can be made easier for your character by having a 'convenient' amputation location, like just below the elbow.