a buenas horas mangas verdes 6
Although you may be missing a comma, I think the phrase can be explained the same. The Holy Brotherhood was a security force in 15th-century Castile to defend the villages from thieves and jumpers, and were distinguished by the green color of the sleeves that peeked out of their leather vests. At first they were very efficient, but eventually they began to delay in getting to the site of the heists, so as not to have to face the criminals. For this reason people shouted with irony "In good hours the green sleeves come!" and the phrase was, already dissolved the police force, to highlight a fact that occurs late, outside the right time.