They will likely teach you how to do excersizes in physical therapy. Don't DIY. For this wobble-board, start out with the good leg planted firmly on the ground, and just use it to flex the ankle joint when the time comes. Only when you are at the point where you can walk with putting full weight on the injured side do you want to climb up on this thing. Start with the easiest setting.
Someone mentioned walking in the sand (when the time comes). This is tremendously beneficial. I hardly ever did it, but really should have (I live on the California coast, and wasted this opportunity). Also, if you can re-learn to walk in a pool, it will make things go a lot easier.
Find a good, hands-on, physical therapist who is willing to push you to the point of agony.