As BW17-BW20 aired yesterday in Taiwan, the next 4 episode block will air on June 24th. Best Wishes schedule on Chunghwa Telecom MOD (中華電信MOD) has been 4 episodes of the last Friday on the month, and
http://www.pikatw.com/ states that BW21-24 (original numbering) which would include the two Rocket Gang episodes are scheduled to air. Korea should be getting pretty close to these episodes as well, so will see later on in June if these episodes premiere outside of Japan first or not.