A Hialeah man sentenced to prison for causing the deaths of a Miami-area couple in a boat crash in the Bahamas was supposed to surrender to authorities on Friday. But at the 11th hour, a federal judge gave him until March to turn himself in — to the dismay of the victims’ relatives. Josbel Fernandez Echevarria was given a reprieve Thursday by U.S. District Judge Kathleen Williams after she first ordered him to surrender immediately at his emotionally charged sentencing hearing last Friday. She then opted to give him a week to put his personal affairs in order. It is unclear why Williams change…