A treaty comes into force upon the “exchange of the instruments of ratification”. This ceremony took place for the Treaty of Versailles in Paris on January 10, 1920.
However, according to the New York Times story on the ceremony, Great Britain ratified for the British Empire as a whole. (This would perhaps make sense, since in 1914 the King declared war, on the advice of this British ministers only, on behalf of the Empire as a whole.) The parties ratifying on 1/10/1920 were Germany, the British Empire, France, Italy, Japan, Belgium, Bolivia, Brazil, Guatemala, Panama, Peru, Poland, Czechoslovakia, Siam, and Uruguay.
You would have to look up when the exchange took place for the other four treaties ending WWI with Austria, Hungary, Bulgaria, and Turkey (St Germaine-en-Laye, Trianon, Neuilly, and Sevres).
The exchange of the instruments of ratification for the peace treaty ending WWII with Japan took place on April 28, 1952, and on that occasion of course both Canada and the United States participated.
There was no peace treaty ending WWII with Germany, because of the division of the country. Each ally terminated the war unilaterally. The US did so on October 19, 1951. Canada did so on July 10, 1951.