Considering that Obi-Wan was Anakin's superior at the beginning of the Clone Wars;

"Take him!" Ventress ordered the super battle droids.

She ran for a side exit. Anakin Skywalker was a powerful Jedi, but she knew Obi-Wan was even stronger.''

The Clone Wars Novel

This is only a couple of months after AotC (or maybe weeks?). But the statement is very clear that Kenobi was stronger than Anakin at some point in the Clone Wars.

I am guessing that he catch-up with Kenobi 1 year after, and after 2 years he has surpassed Kenobi in terms of skill and power considering his duel against Dooku in the Naboo which takes place 2 years after the AotC.

Not really, Dooku is portrayed as his superior;

Hard question... Need to think

Probably mid point within the TCW but it's worth taking into consideration of Anakin's mind state which throughout the course of the war did influence his fighting capabilities from struggling to overwhelming Dooku in some instances.

Well when else would he have surpassed him?

I wouldnt say that anakin surpassed obi wan at any point in unless you count when he was on the son and daughters planet.

@supergoku17: Anakin surpassed Obi-Wan at the end of the Clone Wars according to Nick Gillard, although physically only, not mentally.

Still the difference was not big enough. Yoda said Kenobi can defeat Anakin, but not Sidious.

Alright but in terms of a fight I would say Obi-Wan wins

Midpoint/S4 seems about right.

Well, we can see for ourselves that by Season 6, Anakin had surpassed Obi-Wan's fighting skills if Dooku is any reference point. On their fight on Oba Diah, Dooku clearly had what it took to eliminate Obi-Wan relatively early on. Whereas, Anakin saved him and continued the Count a split second after. Needless to say, though it may have not been by an overwhelming margin, Anakin did perform better in that fight than Obi-Wan did.

It may not be the exact moment when Anakin surpassed, but I believe that is a solid comparison of their abilities at that point in time.

Moreover, Anakin did nearly best Dooku twice in their duel on Naboo. It is difficult to say how much better or worse Obi-Wan would have fared in that same situation. But, somehow, I doubt he would perform as well as Skywalker did, given how Skywalker went for a more overpowering approach instead of a technique more elegant and precise, the latter of which Dooku handles with the utmost of ease.

Mid TCW.

They were equals even as of S6 so probably very late in TCW there

It used to be that Anakin was outperforming Obi-Wan even during AotC. Is that retconned?

Obi-Wan >>> Anakin

Season 4 sounds just about right