more or less, that’s what you should do: create a new domain on DreamHost, fully hosted, get wordpress in it and adjust all the things, then when things are ready, update the DNS records.
Make sure you read this doc https://help.dreamhost.com/hc/en-us/articles/214828548-How-do-I-install-WordPress-before-my-DNS-is-pointed-to-DreamHost- and the related links below to see how to achieve all of that with DreamHost Panel.
I would also suggest you to look into WP-CLI (instead of duplicator). Learning how to use WP-CLI will make things easier also in the future, especially if you administer more than one WordPress site. Check this series of short articles