The healing process will depend on exercising your limb daily. To exercise your residual limb, tighten the remaining muscle by going through the motion of bending your ankle and knee in both legs. It may help to do this with your eyes closed, imagining both legs going through the motion. Contracting and relaxing your limb muscles encourages fluid movement, which promotes healing and reduces swelling.
It's a good idea to inspect your limb daily and after exercising for reddened areas or signs of abrasion. You should also begin to touch and massage your limb as comfort allows. This will help desensitize it, reduce reaction to stimulus and prevent scars from adhering to your bone.
For your below-the-knee amputation:
Never sit or sleep with a pillow under your knee as this will lead to contracture or the inability to straighten the knee.
For your above-the-knee amputation:
Do not sleep with your limb resting on a pillow as this will promote a flexion position and joint tightness.