[Migrants and refugees with their mouths taped stage a protest at a makeshift camp at the Greek-Macedonian border near the village of Idomeni]By Karolina Tagaris LESBOS, Greece (Reuters) - Less than 24 hours before Greece is due to begin returning migrants to Turkey, little sign of preparation is evident on Lesbos, the island through which hundreds of thousands of people have poured into Europe since last year. More than 5,600 migrants have been registered on Greek islands since March 20, the date on which the agreement takes effect. "Planning is in progress," said George Kyritsis, a Greek government spokesman for the migration crisis.