The third war is an interesting matter... let's see
Obito first "death" occured when he was 13, and he was roughly the same age as Kakashi. Kakashi was 26, in the beginning of the series which happened 12 years after the Kyubi attack( where based on these facts Kakashi was 14).
So according to this, the War was on a year before the Kyubi attack.
Another fact we can base our calculations on is the age of the Ame Orphans. Yahiko died 15 yrs old, and Nagato was 35 when he died(roughly 17 yrs after Kyubi attack), which would make him 18 years old during the Kyubi attack. So, if he was born roughly at the same as his team-mates that would lead to conclusion that, that Yahiko's death happened about 2-3 years before the Kyubi attack. Which contradicts the previous paragraph, as we know that Obito's "death" happened before Yahiko's. :( So we don't know which one is the correct...
Another fact we know is that Itachi was 4 years old when he had seen the battlefields of the 3rd war. Itachi was 18 when he appeared in Part 1 ( though this data comes from Databook 2, so we might say that he was only 17 during the very start of the series). So he was around 5-6 during Kyubi attack, that would mean that around 1-2 years before the Kyubi attack the war was definitely on.
As we can see these data are somewhat contradictory, I believe Kishi didn't think it over. I believe that between the "death" of Obito and the death of Rin there was at least 5 months.
I made a rough third war timeline.
(4-5 years before Kyubi Incident)
-Third War Starts
-Akatsuki starts Amegakure Civil Wars ( the actual start may have been before the war, but it surely wage concurrently to the 3rd war for a time)
-Kabuto is found by Nono after a battle
(3-4 years before Kyubi incident)
-Sasori gets the moniker "of the Red Sand"
-Minato gets the moniker "Yellow Flash"
-Kakashi gets promoted to Jonin
-Obito's "Death"
-Destruction of Kannabi Bridge
-Obito healing at Madara's
-Obito awakeaning and training in the cave for a quite a long time
(2-3 years before Kyubi attack)
-Minato fights with A and B
- Rin gets captured
- Obito witnessing Rin's death
- Madara preparing Obito for his role in Tsuki no Me
- Maito Dai dies against the 7 swordsmen
- Madara's death
-Obito aprroaches Ame Orphans
(1-2 years before Kyubi attack)
-Sasori kills the Kazekage and leaves the village
-Searches for the Kazekage
-Orochimaru meets Kabuto for the first time
- Akatsuki with high chances of winning in the Civil War
-Third Raikages's death
-A becomes 4th Raikage
-Because the war was still on Rasa appointed as 4th Kazekage, searches for the 3rd still goes on.
-Yahiko's death, Nagato becomes "Pein"
-Itachi witnesses the terror of the war.
-Third war ended