In the 1660s and early 1670s, the Swedish Empire experienced a financial crisis. In hope of subsidies, Charles XI of Sweden had entered the anti-French Triple Alliance with the Dutch Republic and the Kingdom of England, which broke apart when Charles II of England rapproached France in 1670, after the War of Devolution. In April 1672, Sweden and France concluded an alliance, with France promising 400,000 riksdalers of subsidies in peace time, to be raised to 600,000 in war time, for Sweden maintaining a 16,000 men strong army in her German dominions. Also, Sweden maintained good relations to the Dukes of Holstein-Gottorp south of Denmark. By September 1674, Sweden had enlarged her army to 22,000 men after France had increased the subsidies to 900,000 riksdalers, which she threatened to withdraw if Sweden was not using this army, stationed in Swedish Pomerania, for an attack on her adversaries. By December, the Swedish army had grown to 25,000 to 26,000 men, 4,000 to 5,000 of whom stationed in Bremen, 2,000 to 3,000 in Wismar, 6,000 to 7,000 in Pomeranian garrisons, and 13,000 free to operate under Lord High Constable and field marshal Carl Gustaf Wrangel.
Question: How many months after Sweden enlarged her army to 22,000 men did the Swedish army grown to 25,000 to 26,000?
Answer: 3