You can use the encircled “R” symbol ® once your German trademark has been registered.

Using the ™ symbol with your trademark means that you claim to be the proprietor of the trademark and that you use the trademark as a “source indicator”. You can use the ™ symbol in Germany on registered or unregistered trademarks. However, the encircled “R” symbol ® shows to everybody that you are the owner of a registered trademark.