The Red Army invasion of Georgia , also known as the Soviet-Georgian War or the Soviet invasion of Georgia, was a military campaign by the Soviet Russian  Red Army aimed at overthrowing the Social-Democratic  government of the Democratic Republic of Georgia  and installing a Bolshevik regime in the country. The conflict was a result of expansionist policy by the Soviets, who aimed to control as much as possible of the lands which had been part of the former Russian Empire until the turbulent events of the First World War, as well as the revolutionary efforts of mostly Russian-based Georgian Bolsheviks, who did not have sufficient support in their native country to seize power without external intervention. The independence of Georgia had been recognized by Soviet Russia in the Treaty of Moscow, signed on 7 May 1920, and the subsequent invasion of the country was not universally agreed upon in Moscow. It was largely engineered by two influential Georgian-born Soviet Russian officials, Joseph Stalin and Sergo Ordzhonikidze, who on 14 February 1921 got the consent of Soviet leader Vladimir Lenin to advance into Georgia, on the pretext of supporting  "peasants and workers rebellion" in the country. Soviet forces took the Georgian capital Tbilisi  after heavy fighting and declared the Georgian Soviet Socialist Republic on 25 February 1921. The rest of the country was overrun within three weeks, but it was not until September 1924 that Soviet rule was firmly established. Almost simultaneous occupation of a large portion of southwest Georgia by Turkey  threatened to develop into a crisis between Moscow and Ankara, and led to significant territorial concessions by the Soviets to the Turkish National Government in the Treaty of Kars.
Question: How many years after Soviet forces declared the Georgian Soviet Socialist Republic did the Soviet rule become firmly established?
Answer: 3