A meeting called by Count Plunkett on 19 April 1917 led to the formation of a broad political movement under the banner of Sinn Féin which was formalised at the Sinn Féin Ard Fheis of 25 October 1917. The Conscription Crisis of 1918 further intensified public support for Sinn Féin before the general elections to the British Parliament on 14 December 1918, which resulted in a landslide victory for Sinn Féin, winning 73 seats out of 105, whose MPs gathered in Dublin on 21 January 1919 to form Dáil Éireann and adopt the Declaration of Independence.
Question: How many months passed between the founding of Sinn Fein and it becoming a formal movement?
Answer: 6