I upgraded my site earlier today.
I then informed my registry of the business catalyst nameservers.
How long will it take for my old site to be replaced by my new Muse produced, BC hosted site, to appear?
Have you set up the domain in Business Catalyst as well under site settings > domain management?
If it is a .com it can be up to 24 hours, others can be faster, but for everyone globally its normally about a day.