Nothing yet. The plant is trying to adjust to a new environment. You have to give it some time - plants don't think very fast. Don't be tempted to water until the leaves tell you to.
I got a new Hoya a few days ago. All the tender little shoots have died back but I am confident the plant will like its new surroundings and start growing again. But maybe not today.
PS: Losing old leaves doesn't count. If you start losing new leaves, you have a problem.
Hint: Because of the tightly wrapped leaves, this Hoya is particularly prone to mildew (poor air circulation) and bugs (tight spots). Keep an eye on it.