You don’t need to take it slow. I moved from Gmail to a private email that I manage about 5 years ago. I just put email auto reply on my Gmail saying that I’ve changed my email due to an onslaught of corporate spam. Spammers won’t get the new one because they’re using auto responders, but actual people will get the auto reply and start using your new email address. You can change your email associated with accounts as you log in, or you can just keep those on Google so that the accounts don’t start spamming you on your new email too. The only drawback is that your account won’t be in some big data database and some sign up processes that use services like Informatica might reject your email as invalid since they don’t have a record of it. When that happens just use your Gmail and then update it later.