John Mueller of Google was asked about doing site migrations and if it can impact your SEO. The short answer is that it can impact your SEO but if you do everything correctly it can be a matter of days until everything is back to where it was prior to the migration. But that is a big “if” – if you do it correctly.

He said this at the 37:05 mark in this morning’s video hangout. He said in the old days it would take months for Google to work it out but now if you follow the Google site move help docs exactly and you do everything correctly, it can be a matter of days. It is obviously easier if you move from one domain to another without any other changes but if you change the CMS, the URL structures and make a new site with tons of redirects, Google would have to reprocess the site to understand the changes.

Here is the embed when he said this:

Here is most of the transcript:

Forum discussion at YouTube Community.