I was in therapy and all for quite some time already, so I made the appointment for the first consultation in Munich, which was like three months out, and used that time to get all the indication letters to bring them there already.
This was a time saving measure, you don't need them for that first appointment.
You leave that first appointment with some paperwork you need for filing for the costs with your health insurance, so that happens afterwards - you will also need the indication letters for that.
After the health insurance gives their go, the hospital also needs the indication letters for the second appointment there, which is shortly before the surgery - you get that and the surgery appointment together.