The entire migration process took me a couple of minutes (basically, you just tell your new account that you want to migrate from your old one, then tell your old account where you're going). Now, I think this may be one of the largest follower migrations in fediverse history, so there was a little bit of weirdness in some apps and the website in terms of getting a *ton* of notifications (tens of thousands of follows) but after that settled, it was smooth sailing. And invisible to followers.
@anildash what about your follows? Did it happen automatically too?