On 7 April 1766, Carleton was named acting Lieutenant Governor and Administrator of Quebec with James Murray officially in charge. He arrived in Quebec on 22 September 1766. As Carleton had no experience in public affairs and came from a politically insignificant family, his appointment is unusual and was possibly a surprise to him. One connection may have been due to the Duke of Richmond, who in 1766 been made Secretary of State for the North American colonies. Fourteen years earlier, Carleton had tutored the Duke. The Duke was the colonel of the 72nd Regiment of Foot, while Carleton was its lieutenant colonel. He appointed Carleton as commander-in-chief of all troops stationed in Quebec.  The government consisted of a Governor, a council, and an assembly. The governor could veto any action of the council, but London had also given Carleton instructions that all of his actions required the approval of the council. Most officials of the province at this time did not receive a salary and received their income through fees they charged for their services. Carleton tried to replace this system with one in which the officials received a regular salary, but this position was never supported in London. When Carleton renounced his own fees, Murray was furious.  After Murray resigned his position, Carleton was appointed Captain General and Governor-in-Chief on 12 April 1768. Carleton took the oath of office on 1 November 1768. On 9 August 1770 he sailed for England for what he thought was a few months' consultation on issues related to the integration of Quebec into the British system. During his absence, Hector Theophilus de Cramahe, the lieutenant governor, ran the provincial government, with the aid of the first chief justice, William Hey, and the Attorney-General, Francis Maseres. The British merchants of Quebec, many of whom had become disaffected to the colonial administration under Murray, were, at least initially, of good will. The merchants would later be agent for e.g. the Quebec Act of 1774 (14 Geo. III, c.83) and finally the partition of the two Canadas in the Constitutional Act of 1791 (31 Geo. III, c.31).

Answer this question "When did he become governor?" by extracting the answer from the text above.
7 April 1766,