You can do the towel stretch right away. When the towel stretch is too easy, try the standing calf stretch, soleus stretch, and leg lift. When you no longer have sharp pain in your calf or tendon, you can do the step-up, heel raises, and static and dynamic balance exercises.
Stand upright next to a chair with your injured leg farthest from the chair. This will provide you with support if you need it. Stand just on the foot of your injured leg. Try to raise the arch of this foot while keeping your toes on the floor.