𝐀𝐬𝐩𝐢𝐫𝐢𝐧𝐠 𝐌𝐚𝐬𝐜𝐡𝐞𝐧𝐧𝐲 𝐏𝐞𝐭
I think the answer is yes. Surpassing Oden by blackening Enma would be much less meaningful and impactful if it happens after Wano.
There wouldn't be anyone to properly appreciate the magnitude of the accomplishment.
Gyukimaru and Hitetsu are citizens of Wano. Gyukimaru told us that Ryuma forged Shusui into a Black Blade through his history of battle:
Hitetsu told us that depending on Zoro, Enma's rank may get be raised:
If anyone should witness Zoro forging a Black Blade, it is them.
Kaido is the one who declared that there shall never again be a monster samurai of the likes of Kozuki Oden:
If anyone should recognise the birth of such a samurai, it is him.
Perhaps the Scabbards too should witness Zoro performing the deed.
The connection between Zoro and Oden was further highlighted during his battle with King. Zoro speculated that Oden was able to wield Enma as if it were "as light as a feather":
Blackening Enma and/or surpassing Oden after Wano is just bankrupt of meaning.