When would the EU announce which nations would participate in economic and monetary union?

The European Union typically announces which nations will participate in the Economic and Monetary Union (EMU) during the convergence criteria assessment, which is conducted before the adoption of the euro. This assessment occurs periodically, and decisions are made during European Council meetings, usually held twice a year. The specific timing can vary, but announcements generally follow the completion of evaluations on member states' compliance with the necessary economic criteria.