As far as Naruto turning 17 a day later, we can sum it up this way:
It was about three to six months between when Naruto got back and when Sasuke killed Orochimaru, because he waited until Orochimaru could perform the jutsu again, right? Then to form Team Hebi he had to walk to the southern tip of the map up to the northern tip and then back to the Konoha, considering the fact that it takes three days one way just to go to Suna from Konoha at top speed, and our top speed is about four times the speed of walking—as we can tell, because it took about four days for the Akatsuki to get to that cave from Suna but it only took Naruto's team one day—we can assume it actually takes a few months to get from Orochimaru’s death to Sasuke and Itachi’s battle. This is how the news gets spread of Orochimaru’s death in the time it takes for Team Hebi to form, and how they have the time to track down Itachi despite not knowing all of the Uchiha hide outs like Sasuke would.
From that point, there’s probably at least a week’s worth of travel time and decryption time before Naruto goes to Mount Miyoboku, which takes at least a week in his Sage training, but it’s implied to be a month or two before Pein attacked the village. After all, they had time to study the one path of Pein, Jiraiya killed before Pein arrives and this is between attempting to get the village locked down and prepared for the inevitable assault.
After the Pein attack, it can be assumed to be a month or two before the Kage summit, because Sasuke first has to travel to the Land of Lightning before he can attempt to capture Killer Bee, and then the people carrying the demand for a summit had to travel on foot a distance close to three times that of Konoha to Suna…and we don’t see them running most of the time. By the time they arrive, Konoha is partly rebuilt, and considering how much debris cleaning was involved, and that there was time for carpenters to arrive from other villages, two or three months is reasonable. After all, there needed to be enough time for people to become convinced Tsunade would never wake, so weeks wouldn’t cut it. After that, there would be some time involved to get the Feudal Lord’s attention and presence to convene and decide on a new Hokage before Danzo could have been made the temporary one.
After that, there’s at least a week’s travel time to get to the kage summit from Konoha, considering their attitude toward the trip and the probable distance from Konoha to the Land of Iron. It’s a little misleading because I don’t think all of the flashes back to the village and planning to go after Naruto were synched up with what was going on.
After the summit, another few months had to pass before the war opened up. For one, we see that Konoha is all but completely rebuilt when Sasuke visits with the re-formed Team Taka, which wouldn’t have been worked on once the war began, and it’s long enough that the interrogation squad stopped asking Karin any questions. For another, there was the boat ride up to the Land of Lightning and a second one to the hidden island. According to Captain Yamato’s updates through the trip, it would have been two or three months to get to the Land of Lightning, then however long it took to get to the island, and at least a week before all hell broke out there.
If I only count the months and not the weeks, that’s about 18 months there, or…a year and a half.