For a couple of days many people have been going on about how sloppy Kishi has gotten and how the timeline has gone out of hand.
Kishi, although the creator, is not the only person on the team. He has advisors, image editors and script editors by the dozen. That's how the bloody manga industry works. Do you actually believe that such diligent people would overlook these stuff?

I honestly bunch in these people who call TIMELINE ERROR! with those who start ranting and swearing at Kishi when there's a double issue in Japan. It's like they think he's been slacking off and that's the reason we don't get the manga on a particular week.
Neither Kishi nor his team have anything to do with the manga's publication date. It's all up to the Shonen Jump magazine. They have holidays like every other country. You don't start ranting at the teller when a bank isn't open on a Sunday. It's the same thing.

Anyways, regarding the recent timeline discussions. I'll try to make it clear:

- It's a fact that Hashi was still alive when Tsunade was a toddler.

- It's also a fact that Hashirama died at the same time Tobirama became Hokage.

It says; 初代亡き後その 遺 志を 継 いで゛火影゛と呼ばれたのが、初 代の 実 弟である二代目であった。 which roughly translates to:

After Shodai's death, he (Tobirama) carried on Shodai's will and was called ''Hokage''. The younger brother of the Shodai, was the Nidai.

- It's a fact that Hiruzen is 17-18 years older than Tsunade.
Although I'm not fond of using Narutopedia to prove points, it's pretty useful for such matters.
Here, you can see Tsunade and here; Hiruzen.

- It's certain that Tsunade was 6 years old when she graduated from the Academy and started training under Hiruzen.
Again, have a look here.

- The facts above make Hiruzen 23-24 years old in the following panel.

- Tobirama seems to have appointed Hiruzen as the Hokage when he seems to be just around 20. Give or take a year or two.

Ok, I guess here is where many people get their knickers in a twist.

For the sake of clarification, let's assume that Tsunade was around 2 years old in Hashi's flashback and the death of Hashi came shortly after that instance, making Tobirama the Hokage.

This gives us a four year time span before she starts training with Hiruzen.

During said four year time span, Tobirama dies in battle and appoints Hiruzen as the next Hokage, before he grows a blasted goatee, which seems to be the root of all evil concerning this discussion.

Lets give a year or two for that damned goatee to grow. Just for the sake of doing so.
That still gives Tobirama at least two to three years to reign and accomplish his oh so many feats.

The problem people seem to have is that Tobirama's reign that presumably lasted a year or two seems too short to accomplish all the listed feats as setting up the Konoha police force, a battle or two, injury and recovery, starting up the academy and a bunch of other political stuff.

I assure you that it's not.

Think of how much time passed since the Shippuuden Arc started. It has been just around a year and Konoha has already battled Akatsuki numerous times, saved the Kazekage, helped revive the Kazekage, battled Pein, got completely destroyed down to the rubble, got rebuilt in quite a short time, lost it's Hokage due to a coma for a while, appointed a new Hokage (Danzo), participated in the one and only Kage Summit, lost Danzo, got it's Hokage back, participated in the biggest war in Narutoverse history, battled endless zombie Kages in day one of said war, got it's previous Hokage's zombified by none other than our good ol' Oro and is currently fighting against another boss/overkill/over 9000 zombie that goes by the name of Uchiha Madara accompanied by Obito (another overkill) and, lo and behold, the BLOODY JUUBI!

I hope this gets across.