Its actually this :
Lets say Hashirama becoming the first Hokage and Madara's departure is year 0. This means Shippuden happens in 68/69.
Well in this case, the First War happened in 18 and ended in 20 (two years). Hashirama knew Tsunade when she was 3, and we know he didn't live during the First War. He died at 44, in late 17. His death triggered the First War.
The Second War we know happened 20 years later so that means in 40, and according to what I could find it lasted at least 4 years, so 40-44 (although it could be 40-45, and even 39-45 for all I know 👀)
The Third War ended the same year Naruto was born, si that means in 52 (cause the series begins in this case in 65 and ends in october 69 (Fourth War). Sasori, born in 32, killed the Third Kazekage at the beginning of the war when he was 15, almost 16. This means the Third War at least started in 48, but it could be a bit before. The space between the second and third war is max 4 years thats for sure, but it could be less.
So
FIRST WAR (18-20)
SECOND WAR (40-44)
THIRD WAR (48-52)
FOURTH WAR (Oct. 69)
And also people make a common mistake : the first council of the First Kages happened to end the Warring states period/the wars between the Land of Fire, Lightning, Earth, Water and Wind, not between the villages. It happened in year 1 or 2