Good news, I just recieved the serial-number of my Sling TSi kit. My airplane will be number 517sk and the first parts will hopefully be delivered by the end of the year.
Besides getting the airplane built, there is a bunch of paperwork to be done. I registered myself as a member of the Oskar-Ursinus-Vereinigung (OUV) as they are the responsible party for building experimental aircrafts in Germany. Once the registration on their end was completed, we started working on the first expert report. This report is needed at the Luftfahrt Bundestamt (LBA) to register the project on their end. In addition to that, it confirms the builder has the knowledge and resources (space, workshop, etc.) to actually built the plane.