It sounds like you guys are in GREAT shape. If your dog has bladder control right after surgery, that's wonderful! I totally understand the wish to get on the ball and start doing any therapy that might help, however there is a waiting period after surgery where they advise you to not do active therapy, you just let him heal. http://www.dodgerslist.com/literature/CrateRRP.htm
When you read various websites about IVDD, as you may already be doing, it is important to distinguish between conservative treatment and surgical treatment. The guidelines are a little different. Anything you read, ask yourself, is this information for a dog having conservative treatment or for a dog who had surgery.
Another thing to sort out, which seems off the subject but isn't, is to be sure the information you find is really about IVDD. There is another common cause of paralysis (called FCE, fibrocartilaginous embolism, or "spinal stroke") and the recommendation for that is intensive physical therapy begun soon after the injury. The recommendations for paralyzed dogs with FCE could be harmful for dogs with IVDD, so again when you read anything, ask yourself, is this information for a dog with IVDD or a dog with some other cause of paralysis.
Your surgeon or vet should give you advice on what therapy, if any, is appropriate. My understanding is that only passive therapy is allowed during the crate rest period. Your dog may be allowed to do hydrotherapy (for example swimming) in a few weeks, but only with the doctor's permission. There are websites about hydrotherapy, just ask for the links when you are ready. http://www.dodgerslist.com/literature/m ... rcises.htm
There are some physical therapy modalities that are safe for a dog recovering from surgery, such as cold laser or acupuncture, if it is available and if you can afford it. (I am not a vet or a therapist, check everything with a professional.) http://www.dodgerslist.com/literature/h ... urgery.htm
I do want to say, I don't think you have to worry about your dog walking if his signs are this good already. Congratulations! If it was my dog, I would be very careful and strict about his crate rest period so he does not have a setback, and do passive therapy to keep him flexible but not put any strain on his back while he's healing from his surgery. And also consult with the vet about what kind of therapy he can do and when.
You may want to read more information on Dodgers List, where the above links are taken from.