Guy Carleton, 1st Baron Dorchester, KB (3 September 1724 - 10 November 1808), known between 1776 and 1786 as Sir Guy Carleton, was an Anglo-Irish soldier and administrator. He twice served as Governor of the Province of Quebec, from 1768 to 1778, concurrently serving as Governor General of British North America in that time, and again from 1785 to 1795. The title Baron Dorchester was created on 21 August 1786. He commanded British troops in the American War of Independence, first leading the defence of Quebec during the 1775 rebel invasion and the 1776 counteroffensive that drove the rebels from the province.

Upon his return to England Carleton recommended the creation of a position of Governor General of all the provinces in British North America. Instead he was appointed "Governor-in-chief", with simultaneous appointments as governor of Quebec, New Brunswick, Nova Scotia, and St. John's Island (present-day Prince Edward Island). He arrived in Quebec on 23 October 1786. His position as Governor-in-chief was mostly ignored. He found quickly that his authority in any of the provinces other than Quebec was effective only while he was present in person.  He was raised to the Peerage in August 1786 as Lord Dorchester, Baron of Dorchester in the County of Oxford.  The Constitutional Act of 1791 split the large territory of Quebec into Upper and Lower Canada, corresponding roughly to areas settled by ethnic British and ethnic French, respectively. Sir Alured Clarke was named as the lieutenant governor of Lower Canada and John Graves Simcoe the lieutenant governor of Upper Canada. In August 1791 Carleton left for Britain and on 7 February 1792 took his seat in the House of Lords. He left for Canada again on 18 August 1793 to resume his duties there. His replacement, Robert Prescott, arrived in May 1796. On 9 July 1796 Carleton sailed from Canada to Britain, never to return.  In retirement Carleton lived mostly at Greywell Hill, adjoining Nately Scures, in Hampshire. After about 1805 he moved to Stubbings House at Burchett's Green, near Maidenhead, in Berkshire. On 10 November 1808, he died suddenly at Stubbings. He was buried in the parish church of St Swithun's, Nately Scures.

Using a quote from the above article, answer the following question: when did the post war started
He arrived in Quebec on 23 October