It is quite common to create a 'test' dir. - apeekintoyesterday.com/test

Install Zen Cart there and password protect the 'test' dir. so others (including Search Engines) cannot access it.

Do whatever you and when ready "Copy" your files to where you want them to be. Then you need only to change the URL / Paths within the two config files to be live.

Caution: might want create a new database for when you go live so the two do not use the same database. Then you can continue to use the 'test' setup for testing purposes without interfering / affecting your live site.