How long has dulicate content impact on rankings after getting rid of it?

I am sure some of you have experience with duplicate content.

I have a client that has 5 domains without 301 redirects. That means 5 websites with the exact same content on it.

2 month ago I installed 301 redirects and set up a complete new website.

How long does that duplicate content affect rankings after getting rid of it?

Digital marketing agency in darbhanga