I was in a full length cast from the groin area to my toes when I had my knee surgery. They told me if I damaged it again there would be no way to fix it. The ends of my ligaments and tendons were shredded. They stapled them back together the best they could....
Take it slow. The practice idea is wonderful! Use the crutches like you would a cane, for support with YOU doing most of the actual moving. Use your other foot and leg most, can you do any hopping? If so you could simply put a porta potty by the bed the first week and have a home health aid or a loving hubby to empty and rinse it out.
Keeping that limb elevated and comfy will be your main priority.
If you have to climb stairs this worked for me. Going up, step up with the healthy leg. THEN as you are steady bring up the other leg and the crutches. When going down I found that putting both crutches under one arm and holding the railing worked better for me. I would put the crutch down on the next step, holding the railing tightly with the other hand, then I'd put my weight on the crutch and swing my body and injured limb to the next step. Going down was always harder....
When moving from the bed the first week, always have a spotter there just in case. It may take that long to get the anesthesia and other drugs out of your system. Falling right after surgery is not a good idea. Call a local medical supply or if you can get a temporary home health aid to come ask them about a belt you can Velcro around your waist for a spotter to hold on to.
I worked in a facility once with a woman who was blind, she had to have her breasts removed, and while she was recovering we had a belt to use. It was about 3 inches wide and strong. It have super duper velcro to hold it closed. There were many times she's lose her balance since she was so disoriented and that belt would help us so much.
We'd walk beside her with our arm around her back, our strongest hand would be on the belt. This way if she started going down we could help her slowly down or we could steady her so she could get to a place to sit down.