Domain mapping NEW multisite BASE domain

I've just installed my first multisite from a Bitnami cloud stack. It is now under http://omaapp.bitnamiapp.com/ -> I want it to be omaapp.fi since it is the main blog where I will have all sales etc (and then the subdomains would be site1.omaapp.fi, site2.omaapp.fi etc)...

My present (non cloud) site for omaapp.fi is running still on Hostgator, but I want to transfer to the Bitnami instance.

I read on this site http://wiki.bitnami.org/Applications/BitNami_Wordpress_Multisite#How_to_configure_the_domain_for_the_WordPress_Multisite_main_blog.3f
* to change the domain for your main blog. These options are automatically changed using the following command line tool:
sudo /opt/bitnami/apps/wordpress/updateip --machine_hostname omaapp.fi

I'm not sure should I execute that command BEFORE / AFTER / AT ALL I change DNS records to the IP (dedicated 176.34.191.226) in order to map the site to the wanted dedicated domain name: omaapp.fi