He had advanced CoA way back in Dressrosa. In the timeskip with Wihawk we got to see that he had to master CoA until then he could not drink alcohol.
So he mastered CoA to the point where he could not improve it anymore. Mastering CoA means being able to use CoA at its highest level.
Therefore Zoro had ryou back in Dressrosa or even further right after the timeskip. People coping about Enma being the reason for zoro to use ACoA. But infact he already had it.
Enma only sucked too much ryou out at once. If he hasn't had ryou at the first place enma wouldn't be able to suck it out.
So he mastered CoA to the point where he could not improve it anymore. Mastering CoA means being able to use CoA at its highest level.
Therefore Zoro had ryou back in Dressrosa or even further right after the timeskip. People coping about Enma being the reason for zoro to use ACoA. But infact he already had it.
Enma only sucked too much ryou out at once. If he hasn't had ryou at the first place enma wouldn't be able to suck it out.
