What is the right course of action?

Your answer is correct because you chose to turn before the two cars. According to German traffic rules, when you approach an intersection marked by the priority road sign (a crossroad sign indicating that you must give way to traffic on the intersecting road), you must yield to all vehicles on the priority road.

In this case, the two cars on the left and the right have priority because the sign shows that traffic on the road crossing your street has the right of way. The yellow car on the left and the blue car on the right are both on this priority road and have the right to proceed before you turn.

Therefore, you should wait and only turn once these cars have passed. Turning before the two cars means you respect the priority rule, ensuring safe and lawful driving. Turning after would either mean violating the priority rule or causing confusion and potential danger.

Remember: Always observe priority road signs and give way to vehicles on the main road before you proceed or turn. This keeps traffic flowing safely and legally.