Re: Quick question regarding dog registration.
It's likely fine to wait for your own vet.
The registration appointment is a good 'getting to know you' opportunity; your vet may want to do a routine check, discuss medical history, vaccination plans, etc. So it makes sense to wait until your preferred vet returns from holidays.
It is highly unlikely that you would be questioned, but if you are the fact that the process has been started with the Gemeinde should be sufficient. Simply explain that the vet is on holidays. It is common here, and well understood, that things get put on hold, or grind to a stop, during the holiday times.
Hope Fergus is enjoying his first taste of Switzerland.